TRV / Bypass question

[disinfo]

As you will be able to tell, I have very little idea what I'm talking about when it comes to plumbing work. I am far more electrically biased and as we all know the two don't mix.

Anyway....

I'm doing the bathroom out and have taken the radiator off, this radiator was the only one in the house that didn't have a TRV fitted and was on constantly when the central heating is switched on.

The radiator is going to be off for quite some time now and ideally we'd like the option of using the central heating system.

Do I have to take one of the TRV's off one of the other radiators?

Are there any easy ways of doing this? Do I need to drain the system.

Cheers.

 

[heatserve]

Just take the head off one of your TRVs, this will ensure that there is always an open path.

 

[disinfo]

Just take the head off one of your TRVs, this will ensure that there is always an open path.

Thanks, I was hoping that was the case.

 

[D_Hailsham]

Just take the head off one of your TRVs, this will ensure that there is always an open path.

You can't guarantee that.

If the OP has a system or OV boiler with a Y Plan (OP: that's a single 3-port motorized valve), then it will give an open path if the valve is stuck in CH only position. But if the OP has an S Plan (OP: two 2-port motorized valves), the CH valve will shut when the CH goes off, so there will be no path through any rad, even if it does have a wheel valve and not a TRV.

Combi boilers usually have the diverter set with CH as the default, so a wheel valve will work.

The correct solution would be to fit an Auto-bypass valve and fit a TRV to the bathroom radiator.

 

[disinfo]

If the OP has a system or OV boiler with a Y Plan (OP: that's a single 3-port motorized valve), then it will give an open path if the valve is stuck in CH only position. But if the OP has an S Plan (OP: two 2-port motorized valves), the CH valve will shut when the CH goes off, so there will be no path through any rad, even if it does have a wheel valve and not a TRV.

Combi boilers usually have the diverter set with CH as the default, so a wheel valve will work.

The correct solution would be to fit an Auto-bypass valve and fit a TRV to the bathroom radiator.

Ah bu**er

I'm not sure what we've got really, all I can tell you is that its a combi boiler. It doesn't have a room thermostat (hence the TRV's).

What am I best doing then as a temporary solution allowing me to keep the bathroom radiator disconnected but still use the CH.

Many thanks

 

[D_Hailsham]

I'm not sure what we've got really, all I can tell you is that its a combi boiler.

Then you won't have any external motorized valves, so my remarks about Y and S plan do not apply.

Which make and model boiler do you have? Many have a built in by-pass, so there will be no need to change the TRV to a wheel valve

It doesn't have a room thermostat (hence the TRV's).

You still need a room stat, even when you have TRVs.

 

[disinfo]

Which make and model boiler do you have? Many have a built in by-pass, so there will be no need to change the TRV to a wheel valve.

Its quite an OAP, Worcester 24i

OOI, why the need for a room stat as well?

Its quite a good time for me to put additional wiring in at the moment, so adding one wouldn't be too much of a problem.

Thanks again

 

[Agile]

Imagine its a hot day and all the TRVs have closed!

There is nothing to tell the boiler that no further heat is required in your case.

The reality is that regulations and common sense both require a room stat to turn the boiler off when its heat is not needed.

Tony

 

[disinfo]

Imagine its a hot day and all the TRVs have closed!

There is nothing to tell the boiler that no further heat is required in your case.

The reality is that regulations and common sense both require a room stat to turn the boiler off when its heat is not needed.

Tony

Fair enough, makes sense really.

Sounds like it may also save me a few quid.

I'll get one put in while i'm doing some other wiring.

 

[D_Hailsham]

I'll get one put in while i'm doing some other wiring.

Your boiler does have a built in fixed by-pass, but they also advise keeping one rad permanently open - hence the bathroom rad.

The rad nearest to the thermostat should, ideally, not have a TRV fitted. This is to prevent any possibility of them conflicting. So you could swap the bathroom valve and a TRV (if possible).

The best location for the room thermostat is debatable. The hall and the main living room are the favourites. Do not put it in an area which gets a lot of sun. If you do the room will heat up faster, so the wall stat will shut the boiler off before the other rooms are up to temperature.

Get a decent Digital stat, e.g Honeywell DT90E or DT92E. If you don't have a programmer, the Honeywell CM901, CM907, CM921 and CM927 are very good.