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GomezZz

Right , I spent the whole day arguing with my work partner about the need for an automatic bypass valve. I've been taught that its a requirement where as he says that its not and that its against the 'laws of plumbing' to install TRVS on all rads . He says you have to have one without a TRV on it ??? Is he right ?
 
yes you should leave one rad off without a trv, its good practice.
 
Yes,as said , one radiator is left without a trv on it, to allow correct operation of the system interlock/room thermostat which should be located in same heating space and is not there as a bye pass,a automatic bye pass should still be fitted
This is because although the one radiator may not have a trv on it and in effect not closed down,the balancing valve on the radiator maybe in a to restrictive/closed position, not open enough to allow required circulation around boiler when that rad is the only one on and allowing circulation
This is the case on three port valve system,if two port system,then obviously auto by pass required for when valve is in closed postion
 
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if it is a S plan system you do need an auto by-pass but you would also leave a trv off in the same room as the room stat, so that the rad with no trv cant be turned down as it will regulate the temp in the house via the room stat
 
And just to confuse matters even more
"the boiler is fitted with an automatic integral bypass " Baxi Platinum Combi
 
Right , thanks chaps. So looks like we were both right . You need the auto bypass (if the boiler doesn't already have on installed) And the rad sited in the same room as the room thermostat should be without TRV


cheers
 
its only in regs that you need trv's in bedroom areas iirc. good practice to put them in every room except for the room the stat is in.
 
why is it then that bathroom rads in the main dont have trvs when the stat is in the hallway?
 
its only in regs that you need trv's in bedroom areas iirc. good practice to put them in every room except for the room the stat is in.
It is CHESS basic practice to have:

  1. Time switch
  2. Room stat.
  3. Boiler interlock
  4. TRV's on all rads with the exception of room with stat. fitted.
  5. Automatic bypass valve
why is it then that bathroom rads in the main dont have trvs when the stat is in the hallway?
There is probably no automatic bypass fitted and if there is the installer does not know the basics.
There should NOT be a stat. in room with TRV's fitted as they will conflict against each other.
 
In the dim and distant past when microbore was all the rage with TRV's it became a talking point that the one radiator was not enough of a bypass when all rads were shut it became the norm to leave off the bath trv as well .
As is said above its alll auto bypass now so is not relevant.
We still do it sometimes
 
No its only best practise not a regulation. You can throw the trvs away if you want.

Many modern boilers have integral by passes or ask you to put one in. But that is so they work correctly and keep a minimum flow going or the boiler will burn out especially the composite metal heat exchanger type.
 
No its only best practise not a regulation. You can throw the trvs away if you want.

Many modern boilers have integral by passes or ask you to put one in. But that is so they work correctly and keep a minimum flow going or the boiler will burn out especially the composite metal heat exchanger type.

Trv,s come under part L bypass,s come under MI,s for the correct operation of as you say:)
 
It is CHESS basic practice to have:

  1. Time switch
  2. Room stat.
  3. Boiler interlock
  4. TRV's on all rads with the exception of room with stat. fitted.
  5. Automatic bypass valve

dunno why you quoted me there - i dont see what i said thats any different to you ?
 
There is probably no automatic bypass fitted and if there is the installer does not know the basics.
There should NOT be a stat. in room with TRV's fitted as they will conflict against each other.[/QUOTE]

explain what you mean about auto bypass... if someone fits an auto bypass to the system they don't no basics why?
 
You can fit TRVs to all rads if there is an automatic bypass present and the boiler/system is weather compensated. Otherwise there needs to be one rad left without a trv in the same room as the roomstat which acts as a bypass and allows correct switching temps for the roomstat.

:D

Tezzer
 
You can fit TRVs to all rads if there is an automatic bypass present and the boiler/system is weather compensated. Otherwise there needs to be one rad left without a trv in the same room as the roomstat which acts as a bypass and allows correct switching temps for the roomstat.

:D

Tezzer

dont know why you guys find this so hard??? the trv being left off in the room with a room stat has nothing to do with a by-pass!!!!!!!!!!!!!!!1 totally wrong
the trv is left off becuas eit can conflict, or so they say. people used to leave one trv off to act as a by-pass, now we should be fitting auto bypass valves as they are more efficient and better for the system, simpless
 
dont know why you guys find this so hard??? the trv being left off in the room with a room stat has nothing to do with a by-pass!!!!!!!!!!!!!!!1 totally wrong
the trv is left off becuas eit can conflict, or so they say. people used to leave one trv off to act as a by-pass, now we should be fitting auto bypass valves as they are more efficient and better for the system, simpless

you,re absolutely right there fuzzy well said:D:D
 
It does have something to do with a bypass if an automatic one has not been fitted and you are looking at an existing system!!! We are not finding it hard fuzzy just discussing that we do not live in an ideal world and you may come across situations where the best practice has not been followed or the system you are looking at my be different to what you are used to seeing. I have seen many systems where the ABV has failed and is not opening when it should and caused the boiler to overheat. Try to not be so quick to jump down peoples throats.
 
There is probably no automatic bypass fitted and if there is the installer does not know the basics.
There should NOT be a stat. in room with TRV's fitted as they will conflict against each other.

explain what you mean about auto bypass... if someone fits an auto bypass to the system they don't no basics why?[/QUOTE]

Just noticed this post.
If you look at details above this sentence you quoted, I listed the basic CHESS requirements, but I think tiredness caught up with me in the translation of this sentence you quoted.
What I think I meant was that if a rad bypass was fitted in the bathroom in addition to an automatic bypass then this is wrong and just pointless. I think that is what I was getting at. Not that it is wrong to fit an automatic bypass.
 
explain what you mean about auto bypass... if someone fits an auto bypass to the system they don't no basics why?

Just noticed this post.
If you look at details above this sentence you quoted, I listed the basic CHESS requirements, but I think tiredness caught up with me in the translation of this sentence you quoted.
What I think I meant was that if a rad bypass was fitted in the bathroom in addition to an automatic bypass then this is wrong and just pointless. I think that is what I was getting at. Not that it is wrong to fit an automatic bypass.[/QUOTE]

What if someone turned the bath rad off manually?
 
Just noticed this post.
If you look at details above this sentence you quoted, I listed the basic CHESS requirements, but I think tiredness caught up with me in the translation of this sentence you quoted.
What I think I meant was that if a rad bypass was fitted in the bathroom in addition to an automatic bypass then this is wrong and just pointless. I think that is what I was getting at. Not that it is wrong to fit an automatic bypass.

What if someone turned the bath rad off manually?[/QUOTE]

if u have an auto bypass nothing
 
I know that fuzzy but someone was saying theres no point installing an auto bypass if you have a rad as a bypass. Just spoke to a heating engineer who told me the same thing. But what if someone turns the rad off and there is no bypass? Surely there should be an auto bypass on every new install???
 
I know that fuzzy but someone was saying theres no point installing an auto bypass if you have a rad as a bypass. Just spoke to a heating engineer who told me the same thing. But what if someone turns the rad off and there is no bypass? Surely there should be an auto bypass on every new install???

correct;)
 
its not really automatic it bypasses trough the plate heat and baxi have used a 10mm pipe idea as far back as the first 80 and 105 e,i am with puddle on one rad without a trv always needs to be left off in the room with a roomstat other wise they work against each other
 
Hi Guys,

Need you're expertise please.

My heating system is very basic I don't have a termostat, all I have is a knob on the boiler to turn the heat up on the water.


This was a problem as in the morning I needed the heating on but also the hot water for a shower. But because the central heating water heats the water in my hot water cylinder means i have to crank my boiler up but in turn means my rads go red hot as they didn't have any controls on them except the lounge.

I have five rads in my house 2 x bedrooms, 1 x bathroom, 1 x lounge and 1 x kitchen. I have since fitted two drayton trv4's on the bedrooms the bathroom rad is turned off, the lounge rad has an old fashioned knob which you can turn up and down and the kitchen rad is the same as the bathroom but the valve is constantly stuck on.

I want to fix the Kitchen rad by putting another Drayton TRV4 on but looking around the net i have seen people saying that if you have trv's fiited you need to fit an automatic by pass valve, however I have also read that you can get away without fitting a bypass valve if you leave one rad without a trv to maintain the flow of water although it is not an economical solution.

I was thinking in my case this could work for me because i could stick a TRV on the kitchen rad and then leave the bathroom rad on which would kind of act as a bypass valve.

My only other idea would be to fit a basic thermostatic valve to the rad in the kitchen which i am thinking i should have done at the beginning with the two bedroom rads and taking the trv's off the bedroom rads and replacing those with basic valves too. or fitting a bypass valve.

my boiler is a 1998 glow worm ultimate basic jobbie, please could you confirm the above, I have spent alot researching this on the net and have found nothing so I am thinking there will be alot of people out there which would benefit from this question.

Many Thanks. D
 
You will be fine with just leaving the one rad left open and put TRV's on the others.
But remember the rads will still get as hot, they dont reduce the temp of the water they will just stop that warm now untill they reach the setting you leave them on, which at that point they will shut off.
 
getting a room thermostat fitted would be better, usually hallway/lounge. that area would not want a trv. what controls does the system have, zone valves, cylinder stat, programmer etc.Depending how things are currently set up would determine what work was involved. but with a few changes to controls and maybe pipe work, you could have full control of your heating.
 
Netaheat bypass advice required:

I have a Netaheat Electronic 16/22 boiler with a manual gate valve bypass for the pump over-run between the flow and return after the pump but before either zone valves. The boiler will hopefully be changed for a Worcester Bosch Greenstar 24Ri High Efficiency Boiler towards the end of this summer.

In the meantime I want to fit a Honeywell automatic bypass valve to replace the manual one, but am confused which one to use, DU144 or DU145. There are presuure and capacity differences between the 2 as well as one being angled and one straight. Could someone please advise as to which will be suitable for both boilers so as to minimise the work during the boiler change.

Thank You.
 
Hello shahmk,
I would wait, why go to the bother of draining and filling the system twice.
fitting the bypass when doing the boiler will not be a big job.
 
Why would you need a room stat when you could replace it with a trv,s?. For example in my house I have trv's in all my rooms and I operate the heating from my programmer. I also have an automatic bypass before the motorized valves, so when all trv's are satisfied the pressure rises then automatic bypass kicks in and protects the circulator (pump). Also the other reason why the automatic bypass is a good practice is incase the motorize valves close shut from ware and tear and the boiler is still on the flow will buildup and automatic bypass comes into action.

i am nearly finished my 1st year plumbing apprenticeship so be nice.
 
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