Advice needed. Issues with underfloor heating and hot water system for new build

[Carrera]

Hi, i am looking for advice regarding my system. The plumber/heating engineers have been going round in circles trying different things and I am not sure they're will get to a solution.

The issues -
1. When the underfloor heating is on, the hot water cylinder does not heat up.
2. When heating just the hot water cylinder, the boiler starts cycling heavily.
3. Underfloor heating individual loops, flow rates drop as more manifolds come online.

The system -
Worcester Bosch 40cdi conventional, grundfos Magna 1 pump, Ariston 500 litre hot water cylinder, all located in a basement plant room. There are 6 underfloor heating manifolds, with ports varying from 6 to 10 with differing loop lengths, arranged over 4 floors. The system is controlled via a heatmiser network system with 30 stats in each room. There is also a towel radiator curcuit with 6 rads which we have not yet bought into the combined running equation yet.

The flow out of the boiler goes to the pump, then up to the two feeds to the manifolds ( First feed to 3 manifolds on one side of the house, ground floor, first floor and attic floor, second feed to 2 other manifolds ground floor and first floor and a third feed to the towel rad circuit). Before these feeds there is a T which feeds the hot water cylinder and the final manifold in the basement.

Temperatures at the manifolds in consistent at about 42c and the holier is outputting at 71c.

All zone valves operate correctly, all stats and timers are running and wired correctly.

Heat loss calcis have been done to size the boiler to the heat output required, indicating the boiler is oversized by about 8kw. The system has been in for about a year and it took us a while to figure out why the water was not heating properly.

Effectively when the heating is on the flow does not go through the T to the cylinder, but when the heating is off it does and therefore heats up the water.

Things that have been tried - pump has been upgraded to the one now in place, pipe work taken apart an equivalent of a low loss header using loops and spaced Ts has been tried and then removed. The T has been turned around to reduce resistance.

Any help or advice would be really appreciated as this is driving me nuts.
If I have missed vital information please let me know and I will try and answer.
many thanks in advance.

 

[stevetheplumber]

sounds like you need some balancing valves is the basement manifold of the same feed as the cylinder ? have you tried it with that manifold isolated

 

[Chalked]

If a low loss header was fitted, why wasn't the cylinder piped back to this with its own circulator ? This would have cured it .

 

[bennygas]

No heating of cylinder when underfloor is on? Just an idea, but is the flow temp from the boiler staying high even with all the underfloor calling? The only reason I say this is that I've had a situation like this in the past, and found that if the return coming back from the underfloor is very cold and the boiler can't put enough heat into the water in one pass to raise it to the temperature required for hot water preparation then it can cause similar symptoms. Checked volume/mass flow rate through the boiler and had a look at what the flow and return temps are doing? this doesn't answer the hot water cycling issue though.I guess if this was the case, the solution would be to implement some form of hot water priority set up. Like I say, just an idea.

 

[bennygas]

Is this when someone curses the apprentice who left a gate valve 90% shut....

 

[Carrera]

Thanks for the replies so far, responses:

Stevetheplumber
Basement manifold is off the same feed as the cylinder
if I isolate the basement manifold and just run that, hot water and basement heating work together, as soon as I switch the rest on I loose the hot water cylinder and basement manifold

Chalked
re the low Loss header and and circ back, I will talk to the plumber

Bennygas
re temp being very on return, even if one manifold is running, ie low heat call I still get nothing flowing through the cylinder

 

[Centralheatking]

Hi Carrera -

Welcome to UKPF - you in the right ball park for help - I have read your post
carefully and have some observations and questions.

1. Do you own a porsche motor car - if which model
2.the specifcation you present of your c/h system is top dollar - it has been well designed

so- I think the problem is in the fitting or most likely a component - as it is so new
can you get the installer back ? - my outfit would rtn to problem like this even if is
beyond our promise

3. To help us can you post a diagram of your set up then we can all have a look

Centralheatking

 

[Carrera]

Hi centralheatking,
1 don't own a porsche I wish I did, but all funds have gone into self build.
the installer designed the system,Manx they are in trying to sort it out but going round in circles trying things. I thought I would try and get some fresh views to help as I have to switch between heating and hot water manually at the moment, not what I was expecting.
i will try and put a drawing together of the plant room, but may be easier to take a picture and post it with some annotations. Would that help?
Regards

 

[Gray0689]

Yes a sketch of your system be good

 

[chris watkins]

Things that have been tried - pump has been upgraded to the one now in place, pipe work taken apart an equivalent of a low loss header using loops and spaced Ts has been tried and then removed. The T has been turned around to reduce resistance.

Any help or advice would be really appreciated as this is driving me nuts.
If I have missed vital information please let me know and I will try and answer.
many thanks in advance.

Has there ever been more than one pump on the system ??
You say the original one was upgrades to the Magna but for a LL system to work there must be a constant flow rate through the boiler (as required by the boiler manufacturer) so a dedicated circulator would be required for this & than as a minimum a circulator for the HWS primaries & one for the heating.
Without the required flow rate the temp at the boiler quickly rises & it modulates down.

 

[Carrera]

Has there ever been more than one pump on the system ??
You say the original one was upgrades to the Magna but for a LL system to work there must be a constant flow rate through the boiler (as required by the boiler manufacturer) so a dedicated circulator would be required for this & than as a minimum a circulator for the HWS primaries & one for the heating.
Without the required flow rate the temp at the boiler quickly rises & it modulates down.

Originally one pump, then LL SYSTEM had 3 pumps, one circulating, one feeding heating demand, and one trying to pump round the cylinder (unsuccessful), now back to one pump but a bigger one

 

[Carrera]

I thought would be easier to put in a picture of the plant room rather than a sketch, but having trouble up loading it using the insert picture button. is there a trick to it?

 

[jase158]

I would suggest electrical fault, sounds like the hot water circuit isn't opening when the rest is open. If it all works individually then it is all working but not as it should, either this or a balancing issue. My guess would be an electrical fault though. Possibly one of the 2 port valves not wired correctly

 

[Ermintrude]

If you get ufh up to temp I .e house is at 25 c then lower set points on ufh with cylinder in demand and cyl should heat up if electrical system in correctly. Sounds more like the return from one of the blended returns ( ufh) is running through cylinder ? Balancing / hydraulic issue.

Which cylinder cold switch on hw load . Run until flow is hot , ( run off hot water to ensure demand in cylinder is constant)
Turn on one manifold at a time and wait until the return is at a constant temp, keep working through until you switch one on and cyl flow goes cold. Then you know which one is the prob.

 

[Centralheatking]

Diagram - CHK

 

[Howsie]

Get a decent plumber in.

 

[Ermintrude]

Get a decent plumber in.

You got number for a company who use A team theme tune ? Sure they have this on roughbooks?

 

[Carrera]

Diagram - CHK

I am having trouble uploading a picture of the layout, anyone help?

 

[Carrera]

Don it albeit sideways!
this is the plant room setup

 

[Chalked]

Presumed the cylinder was miles away.! Problem that sticks out to me is why is there a tee off before the pump?
pressure vessel?
another pump? Noooo

 

[Gray0689]

View attachment 16396
Don it albeit sideways!
this is the plant room setup

For the size of house all looks very small !

 

[Ermintrude]

Is that a two or 3 port on cyl? Where do the pipes at bottom on pic disappear to?
Yes the tee under the boiler behind pump also interesting? What's the total load on the heating system as it looks to be 28 and 22 mm

 

[Chalked]

The house has underfloor throughout so output may be ok.
I personally think wb heat exchangers are too restrictive.
a house of this size would have been better served with two smaller boilers on a low loss header. As underfloor does not need a lot of kw, but needs a good flow rate.

 

[Chalked]

Is that a two or 3 port on cyl? Where do the pipes at bottom on pic disappear to?
Yes the tee under the boiler behind pump also interesting? What's the total load on the heating system as it looks to be 28 and 22 mm

Zooming in its a zone valve.

 

[Gray0689]

The house has underfloor throughout so output may be ok.
I personally think wb heat exchangers are too restrictive.
a house of this size would have been better served with two smaller boilers on a low loss header. As underfloor does not need a lot of kw, but needs a good flow rate.

6500sqfoot house
6 manifolds 500litre unvented cylinder
Inch pipe all to small for my liking

 

[Ermintrude]

The house has underfloor throughout so output may be ok.
I personally think wb heat exchangers are too restrictive.
a house of this size would have been better served with two smaller boilers on a low loss header. As underfloor does not need a lot of kw, but needs a good flow rate.

Yes but if cylinder is asking for 18kw and ufh is asking for 15kw possible issue?

 

[Chalked]

At least it's working hard!!!lol

 

[Gray0689]

At least it's working hard!!!lol

That's the point it isn't working

 

[Chalked]

Quick calc for underfloor ( not exact or knowing the property)

1600 square feet = 603-87 m square.

solid floor at 21*c. Works out at roughly 37 kw! Boiler undersized.!


all this does not cure the problem with the cylinder though.

 

[Ray Stafford]

1600 square feet = 603-87 m square.

???

1600 square feet = 149 square metres.

Or am I misunderstanding you?

 

[Gray0689]

???

1600 square feet = 149 square metres.

Or am I misunderstanding you?

House is 6500 square foot ray
500litre cylinder
6 manifolds
7 towel rads

 

[Ray Stafford]

House is 6500 square foot ray
500litre cylinder
6 manifolds
7 towel rads

Gotcha. So original 1600 should have said 6500? Makes sense now. Ta

<memo to self - read the whole thread>

 

[Gray0689]

A low loss header would of been good for that set up
But to be honest I would be thinking the plumber made a hash of that as pipework is undersized
Another good job ruined by cutting corners imho

 

[Ermintrude]

A low loss header would of been good for that set up
But to be honest I would be thinking the plumber made a hash of that as pipework is undersized
Another good job ruined by cutting corners imho

Boiler is a 1/3 of the size it should be ? 604m2 @0.150kw/m2 = 90kw just for the floors! 90kw ain't ever fitting down 28mm unless it's running at 140m/s

 

[Ray Stafford]

Heat loss calcis have been done to size the boiler to the heat output required, indicating the boiler is oversized by about

Any chance of seeing those calcs?

 

[Carrera]

let me try and answer some of the questions, btw the plumber is here at the moment!
Heat loss calcs indicate heating requirement is 27 kW, done prior to boiler selection due to level of insulation, airtightness and mechanical ventilation and heat recovery systems in place.

pipes disappearing down off the picture are flow and return to the basement manifold which sits about 6 feet away

pipework is 28mm most of the way round the house to the manifolds, changing to 22 on the top floor

Flow through hot water cylinder not working even if only one manifold is running, ie extremely low heating load.

The screed on the for is the anhydrite liquid screed, which transfers heat a lot quicker than normal and is only 50 mm thick

the T referred to behind the pump? There is no t behind the pump, the one to the right is flow out, one on the left is just an elbow leading to a T to the cylinder, followed by a T to the basement manifold

 

[Chalked]

Are my eyes deceiving me? I can definitely see two pipes coming down from the boiler, both with tees?
these go off before the pump.

 

[diamondgas]

Without checking for none return valves etc I'd say your problem could be caused by the tee before the pump, unless there's a none-return valve down stream and another pump?

Already mentioned previously, by-the-way !

 

[diamondgas]

The circled bit... 🙂

 

[Carrera]

Ok I see, the two Ts one on flow and one on return leads to manual dead ends that are used to drain system, just a bit beyond the picture, and below that is the system filling loop

 

[Ermintrude]

44kw/m2 you should have ashp or gshp!

 

[Ermintrude]

So have u tried bringing one zone in at a time when sys hot and DHW cylinder is cold? Looks like a pretty messy set up. Was this plumbers first job like this?

 

[Carrera]

So have u tried bringing one zone in at a time when sys hot and DHW cylinder is cold? Looks like a pretty messy set up. Was this plumbers first job like this?

They do houses this size all the time, and say they haven't had this issue crop up before. I have had the same guy, their senior guy, from first fix to final and they have a good reputation.

re bringing hot water online with the system hot and one zone at a time, can you confirm whether you mean one zone or complete manifold?

 

[Gray0689]

So have u tried bringing one zone in at a time when sys hot and DHW cylinder is cold? Looks like a pretty messy set up. Was this plumbers first job like this?

I agree looks like he didn't fully understand what he was going is he new to plumbing large houses looks like it to be honest
I take it hasn't got building control cert yet as not even a bit of lagging
What is your area there maybe a member on here to come and maybe sort you out depending on how the pipework has been left from pic it don't look to tasty to be honest
But that's just my option
Please tell your plumber to join and we can discuss this further

 

[diamondgas]

Ok I see, the two Ts one on flow and one on return leads to manual dead ends that are used to drain system, just a bit beyond the picture, and below that is the system filling loop

Well if that's the case then the water should wizz around the hot water circuit when it's on and, if anything, bi-pass the UFH circuits IMO ... Water will take its easiest route to complete a circuit 🙂

Is that some sort of balancing valve fitted on the return from the cylinder? Is it fully open? Not that it should be, however it's a possibility that it's giving you grief... Otherwise, as mentioned previously, a wiring issue potentially? I don't see any separate zone valves on the individual UFH heating circuits. Are they remote from the 'plant'?

Regards wiring, easy check is that the hot water zone valve is staying open when the heating is on.

I'd bet this was a pig to balance? Also an issue mentioned previously! 🙂

Other possibilities could be a faulty/restricted hot water valve, and or hot water circuit! I think that's also been mentioned? However trying to keep up with all that have posted can be difficult I guess, I am? 🙂 Pump could be an issue? I really am not a fan of the new boys! Could even have a dodgy boiler that's restricting flow?

If your plumbers pulling his hair out then a great indicator of flow issues is temperature difference primary flow and return! I think, if they haven't already done so, I'd be checking each individual circuit to see what they're giving. Any huge difference can help diagnose circulation issues... IMHO 🙂

 

[Chalked]

I think some here are been a little harsh, but back to the subject.

If its the underfloor heating that is messing with the hot water. Have you tried turning each manifold off and let the towel rail and water heat up on their own.

is it possible to post a picture of one of the manifolds to see how they are connected?

 

[Chalked]

Had another thought.
I should be flowing like a good un around the coil, but looking at the picture, could it simply be one of the male threaded fitting that are made into the cylinder having a film of ptfe over the face.
trust me I've seen it a few times.

 

[Gray0689]

I think some here are been a little harsh, but back to the subject.

If its the underfloor heating that is messing with the hot water. Have you tried turning each manifold off and let the towel rail and water heat up on their own.

is it possible to post a picture of one of the manifolds to see how they are connected?

Would you want a £30k to £40k job to look like that!!!!!

 

[Chalked]

Would you want a £30k to £40k job to look like that!!!!!

No mate .:boxing_smiley:
but aren't we trying to get to the root of the problem. Not weather it's lagged !:wink:

 

[Gray0689]

No mate .:boxing_smiley:
but aren't we trying to get to the root of the problem. Not weather it's lagged !:wink:

I don't think it ever going to be right the way it's piped up anyway
It's 6500square foot house over 4 floors probably numerous bathrooms/en suits
I don't see a secondary return pump a 500 litre cylinder
I see one grundfos magna 25-80 doing everything 6manifolds and rad circuit highest bore of pipe 28mm in boiler house a single boiler with no back up
Where going in to light commercial here this is very basic
I don't know full story so it be good if the plumber was on to say his bit as he may of been instructed to do it very cheap as that's the way it's looking

If it was done with a simple header with separate feeds at least the cause be a lot simpler to see and sort out
It should be a simple fix as the cylinder right next to boiler

But will it ever be a great system I don't thing so it will probably work but

 

[diamondgas]

Effectively when the heating is on the flow does not go through the T to the cylinder, but when the heating is off it does and therefore heats up the water.

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO 🙂

 

[Carrera]

I will try and answer some of the points.
Area is south bucks, I would happily pay someone to look and advise me, as I would like to give the plumber the opportunity to put right, and they are trying!

there is a bronze pump for secondary hot water return, just not in the picture it's above the cylinder.

One of the upstairs manifolds sideways!View attachment 16405

Not signed off by building control as the rest is not finished, however we have been living in the house for just under a year, heating was working fine, just not in tandem with the hot water

For the time being the magna pump has been removed and replaced with the old pump, as it isn't working properly, as they are also trying to overcome a flow issue introduced with the recent messing around

Also the non return valve on the flow out from the cylinder has been removed to reduce resistance, however, what is happening now is if the heating is on and the water is switched on, the flow is being pulled backward through the cylinder and cooling the flow up to the heating

 

[Ermintrude]

They do houses this size all the time, and say they haven't had this issue crop up before. I have had the same guy, their senior guy, from first fix to final and they have a good reputation.

re bringing hot water online with the system hot and one zone at a time, can you confirm whether you mean one zone or complete manifold?

Pull one manifold at a time

 

[Carrera]

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO 🙂

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

 

[Gray0689]

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO 🙂

From what I can see of pipework if the umber on site can't see how it not a simple fix the cylinder Is a metre away can't be that many things

 

[Gray0689]

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

What exactly has he tried
Has he checked pump is running when on hot water only
Has he checked pump running on heating and hot water
Has he checked the 2 port is opening when the above Is on
Has the electrical side of things been checked

 

[diamondgas]

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

Temp difference between F&R on hot water only? ... There may be something within the coil of the cylinder itself or , as mentioned, a man made restriction on installation ... PTFE across the pipe opening? A temp check of the flow through the cylinder will quickly tell you whether or not you have a restricted flow. It's then a strip down to find out where it is I'd imagine 🙂

 

[Gray0689]

Your always going to have a flow problem imho as the massive load you will be trying to get out of that 28mm pipe to flow to 6manifolds for that size of a house is just silly

 

[Carrera]

What exactly has he tried
Has he checked pump is running when on hot water only
Has he checked pump running on heating and hot water
Has he checked the 2 port is opening when the above Is on
Has the electrical side of things been checked

All of the above have been checked and checked again

 

[Gray0689]

Did he try blowing out the coil with mains

 

[Ermintrude]

Did he try blowing out the coil with mains

Surely that will blow the mains fuse? 100a through coil?????? Oh water right !

Close all your valves to zones and boiler so only route from loop to drain off is the coil , open filling loop and drain off , open and close drain off to allow pressure to build and remove any bits?? No sawdust or plaster board ore even air in coil??

 

[Carrera]

Did he try blowing out the coil with mains

yes that was done today

 

[mark_mc]

have to agree with gray on this
everything is undersized
if all the circuits go back to the plant room you may be able to solve with a low loss header and pump to each manifold with separate pump
hot water return may be impossible without taking up floors
but would really look at pumping each manifold if possible, and it looks like 22mm doing the manifold in pic which i would be bring 28mm too, better looking at it than looking for it.

 

[Nostrum]

It looks like it could be reverse circulation does the flow/return that lead to the basement have a balancing valve on?

From the picture ( which is very hard to make out on an ipad) flow could be being forced down to the basement circuit then back through the coil and into the flow again which is then leading up to the UFH circuit which would add up with what your saying. A bit like a 1 pipe system.

How I haven't quite figured out yet, are you sure that valve is opening fully?

 

[Nostrum]

Is some of that Pipework 35mm?

 

[Carrera]

It looks like it could be reverse circulation does the flow/return that lead to the basement have a balancing valve on?

From the picture ( which is very hard to make out on an ipad) flow could be being forced down to the basement circuit then back through the coil and into the flow again which is then leading up to the UFH circuit which would add up with what your saying. A bit like a 1 pipe system.

How I haven't quite figured out yet, are you sure that valve is opening fully?

valve is definitely opening up properly
some pope work in the basement is greater that 28mm

 

[Gray0689]

valve is definitely opening up properly
some pope work in the basement is greater that 28mm

The flow return from boiler is 28mm

 

[Nostrum]

Yeah if you look at the right hand side 'manifold' 2 are 28mm up to the UFH and the one on the far right is 22mm, there is a reducer before hey tee so it must be 35mm, it then reduces on the tee under the boiler, so flow out of boiler is 28mm into a 35mm tee. That why the pump doesn't have standard valves.

If you isolate the basement manifold does your cylinder stop reverse circulating?

 

[stevetheplumber]

all looks well undersized to me

 

[Carrera]

Yeah if you look at the right hand side 'manifold' 2 are 28mm up to the UFH and the one on the far right is 22mm, there is a reducer before hey tee so it must be 35mm, it then reduces on the tee under the boiler, so flow out of boiler is 28mm into a 35mm tee. That why the pump doesn't have standard valves.

If you isolate the basement manifold does your cylinder stop reverse circulating?

Will have to test tomorrow and get back to you

 

[Ermintrude]

Can I come and fix it for u? I'm reasonable and will get it working 100%

Not cheap not by a long way one 3k plus materials

 

[mark_mc]

we are all hitting are head against a brick wall, as we can all agree the install is undersized and that we would all have done it another way.
its now at the point it seems that the poor plumber that put it know that to.
its undersized a large cylinder requires independent 28mm flow and return in most cases.

 

[Gray0689]

Will have to test tomorrow and get back to you

Tell you plumber you make you out a sketch of the pipe work then we will be able to get a better look
Who specced the job for that kind of size I'd like to think there was a me consultation in design

 

[Ermintrude]

Tell you plumber you make you out a sketch of the pipe work then we will be able to get a better look
Who specced the job for that kind of size I'd like to think there was a me consultation in design

Nope but his mate knows all about boilers n stuff

 

[Nostrum]

Guys, look at the picture, this isn't undersized, its 35mm and 28mm. The picture is deceiving but it is larger Pipework than you think.

 

[Nostrum]

Carrera, the flow to hot water cylinder valve tees off the main run as it were, then before it gets to the hot water zone valve it tees off again, what's that for?

this is a Pipework issue, I'm sure of it, somewhere in that plant room, maybe with a combination of balancing chucked in as well.

 

[mark_mc]

NOT WORKING

undersized / designed wrong / needed re-done/

 

[Nostrum]

NOT WORKING

undersized / designed wrong / needed re-done/

very helpful. If it were undersized Pipework the cylinder would be robbing all the heat as the resistance to UFH would be too high.

 

[Nostrum]

And putting the smaller pump back in and it still working the same as it was is proof of that.

 

[mark_mc]

Its getting to ufh circuits but i bet its getting there great.
look at the resistance str after the pump you have the t's for the cylinder and which way would the water rather go-- to the ufh
and then you have the t's of to the flow return to the basement ufh manifold
to much resistance - no thinking in what way the water would behave
if you where honest looking at that pic you would never install it that way, its just wrong.
if it was pumped independently everything would work



i always price so that it works with zero defects and that comes with a extra cost.

 

[Gray0689]

Guys, look at the picture, this isn't undersized, its 35mm and 28mm. The picture is deceiving but it is larger Pipework than you think.

It's undersized it needs a low loss header and re piped properly
As already said big drop at flow meters is a big giveaway

 

[Carrera]

Carrera, the flow to hot water cylinder valve tees off the main run as it were, then before it gets to the hot water zone valve it tees off again, what's that for?

this is a Pipework issue, I'm sure of it, somewhere in that plant room, maybe with a combination of balancing chucked in as well.

That next T leads to the small basement manifold which is also located in the plant room

 

[Gray0689]

And putting the smaller pump back in and it still working the same as it was is proof of that.

The manifolds are pumped the magna is acting as a shunt pump
It can't get enough flow through that 28mm IMO

 

[Nostrum]

Yes I agree I wouldn't have installed it anything like that and agree with you, always fit it right the first time dare than go back replacing the corners you have cut.

but just saying rip it out and start again is not a great help, and this fault is due to a different fault IMO.

He reality is no one really knows how well it's going to work once sorted, but when you are as balls deep as this now, it's worth trying to rectify before chucking the towel in completely. It's not the O.P's fault, whatever the price someone has been contracted to carry out this work. If they are confident they can get it running with this design then give them the benefit of the doubt.

if the O.P decides once/if it is running that it's not good enough, that is the time to question the design.

Whilst it's not our job to rectify, the post is asking for advice.

Its one of the more interesting posts anyway!

 

[Gray0689]

That next T leads to the small basement manifold which is also located in the plant room

I know it's not what you want to hear mate but we are just trying to help where not just slating your plumbers work you have a problem I'm sure you paid big money for this job

Plumbing is a funny thing it could be plumbed crap but it can work as far as the customer is concerned as long as he turns the heAt on he gets heat it's grand but unfortunately that's not the case
For a smaller house your set up probably be grand but not a house that size
It really should of been designed by a M&E consultant with spec they would not do it that way I can guarantee that

 

[Nostrum]

The manifolds are pumped the magna is acting as a shunt pump
It can't get enough flow through that 28mm IMO

are you sure, where's the pump for the cylinder , the bypass circuit and why is the pump wired directly to the boiler?

 

[Gray0689]

Yes I agree I wouldn't have installed it anything like that and agree with you, always fit it right the first time dare than go back replacing the corners you have cut.

but just saying rip it out and start again is not a great help, and this fault is due to a different fault IMO.

He reality is no one really knows how well it's going to work once sorted, but when you are as balls deep as this now, it's worth trying to rectify before chucking the towel in completely. It's not the O.P's fault, whatever the price someone has been contracted to carry out this work. If they are confident they can get it running with this design then give them the benefit of the doubt.

if the O.P decides once/if it is running that it's not good enough, that is the time to question the design.

Whilst it's not our job to rectify, the post is asking for advice.

Its one of the more interesting posts anyway!

Looking at a bad picture of half an installation don't think where going to see the full picture
Yes he ha asked for advice and I do believe he has had good advice
The bet seems to have checked all the normal causes that it could be so now need to look at it deeper
As all were doing is just guessing now but as almost everyone has stated already it looks undersized

 

[Gray0689]

are you sure, where's the pump for the cylinder , the bypass circuit and why is the pump wired directly to the boiler?

The magna is the pump for cylinder
Ps I'm not an electricians ask me one I know lol

 

[Nostrum]

Well, maybe that's where we disagree, looks like 35mm and 28mm UFH circuits with 22mm towel rail circuit to me. Can't be sure but the hw circuit looks like it could be 28mm as well.

 

[Gray0689]

Well, maybe that's where we disagree, looks like 35mm and 28mm UFH circuits with 22mm towel rail circuit to me. Can't be sure but the hw circuit looks like it could be 28mm as well.

Yes there is some 35mm but coming off 28mm from boiler the 35mm is useless

 

[Gray0689]

Well, maybe that's where we disagree, looks like 35mm and 28mm UFH circuits with 22mm towel rail circuit to me. Can't be sure but the hw circuit looks like it could be 28mm as well.

To me when the underfloor and hot water on together
The flow that all them manifolds need and don't forget 6 pumps going and a shunt pump there starving the hot water coil the wY it's plumbed


As has been said a few times if you was to shut down manifolds one at a time eventually you will get the heating and hot water going
But needs re plumbed

 

[Carrera]

I welcome all the input, I am not trying to defend or slate the plumber. I am just trying to get to a working system. I am not wedded to this or any other design.

Yes I paid a lot for the install, wasn't the cheapest quote, but these guys do 6 or 7 houses this size or similar and came recommended.

design was left to them, as it is on most of there jobs.

ripping up floors is not an option, ufh pipes are in.

ripping down ceilings is something I don't really want to do, and without doing this I cannot plumb the manifolds back separately

i am just getting slated at the monument by the wife and kids every time the hot water isn't hot!

 

[mark_mc]

put the immersion on, and enjoy christmas.

it will get sorted with the help from this forum

 

[Carrera]

Even with only one manifold going the hot water doe not work with the heating

 

[Carrera]

put the immersion on, and enjoy christmas.

it will get sorted with the help from this forum

6kw immersion does nothing to a 500 litre cylinder!

 

[mark_mc]

crap.

 

[Gray0689]

To me the only way to do this now

1 put in a low loss header and re pipe the boiler room
Separate feeds to the underfloor pipework you have in place
Separate feeds to rad circuit
And separate to cylinder
All with there own pumps there letting them work on there own

Or if you have the room I'd put in a buffer tank
And pipe from buffer


It's hard for you I understand as your the one who gets the grief at home and then listening to advice here I'm the worst for making it sound like I'm just slating the plumber not the best at making posts sound nice and friendly but
I don't blame the boy on site as he probably been told to do it that way
And on a smaller house probably be no problem at all

 

[mark_mc]

how many circuits can we divid the system into as it sits without lifting floorboards/causing too much damage

 

[Gray0689]

Looks to me 6 manifolds 3flows 3 returns and flow return to rad circuit

Do you have the sheet with the calcs for the underfloor Spec manifold sizes pipe length ect

 

[mark_mc]

buffer would be a good idea.
only gas at the minute and in the future you will be looking at more heat sources and buffer ideal for that.