Scalding hot water and radiators.

[Dotty]

As ever grandpappy comes in with the voice of reason. ...

 

[tamz]

Nothing worth watching on the telly tonight John i'm even thinking of having an early night

 

[Masood]

You are not wrong. It is a common misconception that a TRV provides a radiator with cooler water from the system.

I absolutely did not say that! It can't provide cooler water as there is no way of cooling it until it's in the rad...

 

[Masood]

I get where you're coming from but I disagree.

Let's look at a scenario ! If only to demonstrate my point .

It's the dead of winter and the house is cold, around 14 degrees c , it's early morning and the heating has been off all night.

The heating comes on, the TRV's are all open fully. That radiator, until the room temp starts to pass 16 degrees will be on the full temp that the boiler stat is set to.

I follow what you mean, in that, the warmer the room the lower the surface temp of the rads.

However, just because you install a TRV, you are not necessarily going to prevent high surface temperatures and you shouldn't suggest to a customer that installing one will prevent their child from burning themselves.

Am I wrong in your opinion ?

I don't think you're 100% wrong but a decent TRV will start to modulate almost immediately. Remember the boiler stat will also do the same - allow full power initially and then start modulating...

 

[Last Plumber]

I don't think you're 100% wrong but a decent TRV will start to modulate almost immediately. Remember the boiler stat will also do the same - allow full power initially and then start modulating...

Not modulating on this boiler masood. Simple on off stat. Will go straight to 82 deg if set on Max and then off. What's more, it will maintain that temperature.

Even modern good quality TRV can fail or if the room is cold it will be open fully until room warms.

This is starting to get off the track now but, in order to prevent high temp on rads, you need
Low surface temp rads. There are other methods of course but like I say, we're getting of the thread I think.

 

[Joebananas]

Thank you so much everyone for your input. I really appreciate it. This is a really helpful forum.I spoke to a boiler engineer last night (I felt really sorry for the chap - I went through our boiler cover which is with Homeserve, they offered my a slot today and he phoned last night and tried to sort the problem over the phone at 8pm. Get the feeling that Homeserve work their sub-contractors quite hard??) Anyway, he said to turn the boiler stat down to min and then leave it 24 hours. The water does seem marginally cooler this morn but really only a little bit. Is turning the stat down to min really going to solve the problem?? Sounds like it's just moving the problem around to me and that actually it needs fixing properly?? Any further advice greatly appreciated. Just to clarify, I turned the stat on the tank in the airing cupboard down to about 40 yesterday lunchtime and the stat on the boiler down to 3, then turned the boiler stat down to min at 8pm last night. The timer for heating the water comes on twice a day for 2 hours in the morn and 1 in the eve before kids bathtime (if that's helpful?)
Thank folks!

 

[Masood]

Not modulating on this boiler masood. Simple on off stat. Will go straight to 82 deg if set on Max and then off. What's more, it will maintain that temperature

I was talking general rather than specifically about this boiler, and boiler stats can also fail, sp that's not an ideal solution either

But yes, we're going off topic!