Some questions regarding my hot water system please?

[Steve_B]

Hi all,

As per my intro post, the time has come to get to grips with the hot water system in my house so I have a few questions if I may? I'm trying to learn the layout of it all so please accept my apologies if anything I ask is stupid. I have done lots of research before posting so hopefully the info I provide will be logical...


I'm sure it'll help if I explain the setup:

The water supply features a pretty old central heating system including a Thorn M44/54C boiler in the kitchen, cylinder in the airing cupbard, a CW tank and a separate expansion tank, both in loft. Rads are a mix of single and double convector, with standard on/off valves.
All cold water (inc bathroom) is fed from the rising main.

This is the general makeup of the hot water pipes etc:

(clicky thumbs...)





I have traced the pipes as best I can and researched online and I think I have it labelled up right in the above.

I believe I have a gravity fed, indirect, vented system. Does this look right to you?


The shower is an old Mira mixer (non thermostatic, non power) and the first problem I would like to resolve is the slow flow and the 1mm difference between freezing and boiling. I changed all the washers and o-rings in it last weekend as it was leaking terribly. I had hoped it would improve the flow but it hasn't...

The vertical distance from the shower head to the bottom of the CW tank is 20 inches which doesn't seem a lot...

I've ready many forums etc and I understand the basic options are to either: raise the CW tank, replace the shower with a power shower, or install a pump. I'm not keen on a pump and I'm unsure if a power shower will be a worthy investment (may as well get an electric one installed instead?).



So the first question batch if I may:
Would raising the CW tank in the loft by 1 metre make a worthwhile difference (considering when I dropped the shower head 1m there was no noticeable flow increase - or is this a red herring)?
From research, others who have asked the question on the net have recieved mixed responses to this question so I'm unsure if I should bother...

What I did notice however, was by dropping the shower head, I can control the temperature a lot more accurately. I assume this is because the extra metre allows just enough extra hot water to balance with the cold from the mains?
If this is the case I think it's worth raising the tank just for that alone.

If I do raise the CW tank, will I need to raise the small expansion tank too? I read one article that said if you don't, you can flood the loft but I'm not sure why this would... ?


Also, could someone please explain why is there an expansion pipe into both the tanks? I assume one is not in use and the cylinder leads to the active one, but how can I discover which (the water in both tanks is cold at all times)?

EDIT: Oh, and sorry, one more, the CW tank is 24"W * 23"L *19"D with the water up to 16". I calculate this as about 30 gallons. This seems small. Would a bigger tank give substantially more pressure, as in theory there would be more water weight pushing on the outlet?

Thanks for taking the time to read this and for any help you're able to give.
Regards
Steve

 

[Puddle]

Hi all,



I believe I have a gravity fed, indirect, vented system. Does this look right to you?

It seems you do have a gravity system by pipework shown,this should be updated,as very inefficient and with energy costing what it does and set to rise,update would easily pay for its self and give you better control of hot water for shower mixing and safety,another reason your existing shower should have been thermostatic as if manual,easy to burn yourself

The shower is an old Mira mixer (non thermostatic, non power) and the first problem I would like to resolve is the slow flow and the 1mm difference between freezing and boiling. I changed all the washers and o-rings in it last weekend as it was leaking terribly. I had hoped it would improve the flow but it hasn't...

This is because you have mains cold and hot from tank ,a very dangerous why to plumb in a shower,especially as hot on gravity,if cold turned off in street or someone turns kitchen mains tap on ect,you will be scolded,especially with a manual mixer,I would not take a shower in a set up like this

The vertical distance from the shower head to the bottom of the CW tank is 20 inches which doesn't seem a lot...

I've ready many forums etc and I understand the basic options are to either: raise the CW tank, replace the shower with a power shower, or install a pump. I'm not keen on a pump and I'm unsure if a power shower will be a worthy investment (may as well get an electric one installed instead?).

You can not fit a pump on this system, fitting a pump in ,would have to be after the shower mixer valve as temp of gravity hot water will damage pump and if you fit after the mixer ,the cold mains pressure will damage it.if you have a flexible shower hose from shower,a way to get a reasonable shower,with your set up would be to run a cold feed from the tank in roof to shower ,removing mains supply,as fit one of these

Booster Pumps



So the first question batch if I may:
Would raising the CW tank in the loft by 1 metre make a worthwhile difference (considering when I dropped the shower head 1m there was no noticeable flow increase - or is this a red herring)?
From research, others who have asked the question on the net have recieved mixed responses to this question so I'm unsure if I should bother...

The shower you like is personal preference ,however most people want a good shower these days,old set ups like this are not really acceptable
Urgent works needed,is for you to replace the two galvanized tanks with plastic,having these is a flood just waiting to happen,as you should replace tanks ,as soon as possible,raise the storage tank at the same time,it will give an improvement


What I did notice however, was by dropping the shower head, I can control the temperature a lot more accurately. I assume this is because the extra metre allows just enough extra hot water to balance with the cold from the mains?
If this is the case I think it's worth raising the tank just for that alone.

If I do raise the CW tank, will I need to raise the small expansion tank too? I read one article that said if you don't, you can flood the loft but I'm not sure why this would... ?

No you do not,separate systems,not connected,you could get water from one to tuther if coil split however,overflow would take care of this,if you were paranoid you would put both tank water levels at the same height,not tanks,however just as many would say by doing this if you did have cross contamination ,you would not know,as overflow warning sign would be gone

Also, could someone please explain why is there an expansion pipe into both the tanks? I assume one is not in use and the cylinder leads to the active one, but how can I discover which (the water in both tanks is cold at all times)?

You have two expansion pipes,this is correct,one for heating/boiler expansion over header tank and one for cylinder required for when water heated in cylinder

EDIT: Oh, and sorry, one more, the CW tank is 24"W * 23"L *19"D with the water up to 16". I calculate this as about 30 gallons. This seems small. Would a bigger tank give substantially more pressure, as in theory there would be more water weight pushing on the outlet?

You should increase tank size when you update tanks asap to at least 50 gal as at present to small and fit full by law kits for your health

in theory pressure will be increased but in reality,nothing to notice through shower by increasing tank size

Thanks for taking the time to read this and for any help you're able to give.
Regards
Steve

I would say ,think about what you have ,its condition and how much it is to run and you will go for a complete up date of system,it makes so much sense
There is no reason to try to keep what you have,it is dangerous,expensive to run and has far past its sell by date... and that shower be so. so careful,

 

[tipintim]

Lots of visable brobs I see.
You say that your cylinder is being feed from cold water tank with a 15mm pipe. Should be at least 22.
Galvanised tanks are a breeding ground for legionella and other bacterium
Vent pipe looks to be below water line
No lids on tanks. By law 30
As puddle says, time to up grade.

If you were to raise tank, yes it would benifit your shower. While you have drained system down, replace tank with new.

 

[justlead1]

Hi. Increasing the size/capacity of CWSC will not give more pressure/volume. But raising the level will. As have bee said the minimum size of cold feed to cylinder is 22 mm. Both the CWSC and Expansion cistern with have a pipe venting over them. The expansion cistern does not need to be raised. The hot draw off from the cylinder run in 22 mm too as near as possible to the shower will give better results along with raising CWSC. Good Luck

 

[Puddle]

The cold feed to the cylinder is 22mm from picture,looks like incorrect details on drawing

 

[joe brown]

those tanks look disgusting mate, but yes if you raised it you would get better flow, you would have to raise it quite a bit higher to notice the difference

 

[Avatar]

Why not swap your system over to a nice combi boiler system, which would upgrade everything, bar the radiator network. And this would provide a decent shower as well!

 

[PlumbBobBob]

good idea avatar, system certainly needs updating.

 

[Steve_B]

Firstly thank you to everyone who has replied and for all the advice. Having taken some time to think about it, unfortunately I don't have the funds to complete a system replacement, so for now it'll have to be make do.

First up is the shower. I have decided to take advantage of the existing CW mains and install an electric shower (Homebase have a couple of different 9.5kw Miras reduced to around £100 at present which seems a good deal).
I'm confident I can remove and cap the current mixer and install the shower unit.
I can also create a channel for the electric cable down to the consumer unit.
Trouble is, I spoke to a family friend today who did the same thing very recently and he cannot get any reputable local sparky to run the wiring and connect it all. They all want to do the whole job so he's now stuck with a non working shower. Is this a common occurrence?

It looks like for a number of reasons it's prudent to do the tanks so thanks for the help with those. I'll get onto those.

Thanks again.

The cold feed to the cylinder is 22mm from picture,looks like incorrect details on drawing

Thanks - my bad (it was late when I drew that)

 

[Avatar]

Mate seriously check out the situation wether you can install the electric shower easily, electrical work can easily be another 2-300 plus a whole lot more if you need a brand new board . . .

A lot of the time I reccommend customers not to do it. It doesn't reallyu solve your problems, and its a lot of dough to cough up!

Actually an impeller pump would be a vheaper option on the electrical side, but I have a nasty feeling that you would need an expensive negative head pump.

Putting a combi on a system like yours might not cost as much as you thinmk by the way, esepcially if you can dpo some of the work yourself!

 

[Steve_B]

Ok thanks, in that case I'll look into all the options a bit more first.

 

[alder]

You could easily end up chucking £500 down the drain only to find later on you have to upgrade to a combi anyway! I have been to 6 houses in December wrecked by burst pipes in the loft! Combi is so much better on many levels and the best thing about a combi is that it pays you back on your heating bills!

 

[PlumbBobBob]

and as you know with a combi you do away with the tanks in the loft anyway saving having to replace them.