Tado / Bypass Radiator

[Mister Banks]

I know.

I'm doing a lot of research to get clarity on this because my old non condensing boiler which doesn't really care about return temps, etc is getting long in the tooth.

No official or advisory groups mention it though.

I get that those doing this for decades may be thinking wtf at the idea of not doing it but i am coming at it from the other side.

Why do it at all?

Not really had many structured answers so far.

On a condensing gas boiler I don’t think the boiler will ever go into condensing mode without the radiators being balanced, the return temp will always be to high. This will be effect efficiency and hence gas usage.

 

[BlueLoo]

On a condensing gas boiler I don’t think the boiler will ever go into condensing mode without the radiators being balanced, the return temp will always be to high. This will be effect efficiency and hence gas usage.

Aye,
Assuming fixed speed pumps.
Modern pumps are proportional.
Modern boilers modulate.

But certainly, it's a lot of variation.

A modern boiler in non condensing mode is still more efficient than an old non condensing boiler.

Heating a large space (or all zones) will still be in condensing mode.

The problem comes when the majority of the rads are satisfied and flow rates drop, knocking the boiler out of condensation.

But, do you hobble the existing system to cope with the low heat input case? I don't think so. Let the system be as quck as it can be, then you'll have the boiler running less and thus you can keep the on-off fluctuations to a min.

However, there is a huge push for low temp heating and low heat loss housing design and retrofit which needs high flow rates and low water temps in big rads.

I find it counter intuitive to upgrade the system for higher potential heat output and then stand on its throat in the name of balancing.

Better to slow the flow at the pump, than at the emmiter?

Complex problems. Not easily solved by rules of thimb and look up charts the industry is used too.


(Sorry to the OP for going OT!)

 

[gjw123]

Thanks for all the replies everyone. Just FYI, before coming on here put out some feelers with local trades people. In line with your view BlueLoo, one came back and said I shouldn't need an ABV as I have a three port valve and a manual bypass.

In terms of changing over the manual valve on the radiator in the picture attached, would this be a case of just needing to change the flow valve to a TRV and leaving the return as is, or would I need to change that too?

I'm presuming this isn't a particularly tricky job to do (change a manual valve to a TRV)?

 

[BlueLoo]

Thanks for all the replies everyone. Just FYI, before coming on here put out some feelers with local trades people. In line with your view BlueLoo, one came back and said I shouldn't need an ABV as I have a three port valve and a manual bypass.

In terms of changing over the manual valve on the radiator in the picture attached, would this be a case of just needing to change the flow valve to a TRV and leaving the return as is, or would I need to change that too?

I'm presuming this isn't a particularly tricky job to do (change a manual valve to a TRV)?

Dead easy but as always, it's only easy if you've done it before....

Plenty of vids online.

You can get just the trv bodies without the head. I used Myson but take your pick. Just be careful to match the finish.

Also, the Myson valves are bidirectional meaning (in your case) you can have the head pointing as per yours are now (a trip hazard) or parallel with the wall (which is what i did on mine).

My understanding is that whilst they can go either side (bi directional) it's better for them to be on the flow.

Check dimensions of whatever you get to make sure they will swap over (should be std).

The tricky bit is not drowning the gaff when you do the swap.
I drained my system down when i fitted mine.

I've also bunged up the head tank (unvented) and not drained when i changed just one. It was just about ok.....

If you drain down, you'll have to refill properly and do all the other things. Not a huge job but it has it's own needs.

YouTube is full of vids.

 

[gjw123]

Dead easy but as always, it's only easy if you've done it before....

Plenty of vids online.

You can get just the trv bodies without the head. I used Myson but take your pick. Just be careful to match the finish.

Also, the Myson valves are bidirectional meaning (in your case) you can have the head pointing as per yours are now (a trip hazard) or parallel with the wall (which is what i did on mine).

My understanding is that whilst they can go either side (bi directional) it's better for them to be on the flow.

Check dimensions of whatever you get to make sure they will swap over (should be std).

The tricky bit is not drowning the gaff when you do the swap.
I drained my system down when i fitted mine.

I've also bunged up the head tank (unvented) and not drained when i changed just one. It was just about ok.....

If you drain down, you'll have to refill properly and do all the other things. Not a huge job but it has it's own needs.

YouTube is full of vids.

Great, thanks for the advice! Would you say that both valves need to be changed (TRV & lockshield), or just swapping over to the TRV?

 

[BlueLoo]

Great, thanks for the advice! Would you say that both valves need to be changed (TRV & lockshield), or just swapping over to the TRV?

You only need the one (trv).

But I'd do both and change the other to a lockshield.

 

[gjw123]

You only need the one (trv).

But I'd do both and change the other to a lockshield.

Grand, thanks!

I had further comments from the plumber, who said he didn't think I'd need one, as I have a manual bypass and three port valve which never stop flow. I'm presuming this (including the three port valve) was in line with what you were saying?