Three Port Valve

[Deleted member 15266]

We have an issue with the radiators coming on with hot water only. Engineer changed the three port valve. It worked as it should but the same night and since reverted to heating the radiators again. Engineer thinks it may be doing a bypass because non of the radiators have TVRs on and adding them may solve the problem. I’m not sure and don’t want to waste more money if it won’t work. What do you guys think?

 

[ericmark]

I have had thermo-syphon heating upper floor radiators, but not radiators on same level as boiler. I have also seen it where some one has cheated and latched the three port valve open, have you checked?

As to TRV's I would fit them anyway, but the question is which type? Mine are electronic but not linked to the wall thermostat, my late mothers were the same, with my house it does not work that well as hall where thermostat is cools too slow, but mothers house worked A1, so it seems it does depend on the house.

There is also a difference with my 14 radiators to mothers 8, so also likely depends on size of house.

But what is the point in paying an heating and ventilation engineer then not taking his advice, to be classed an engineer means over level 3 training, i.e. went to University, he should know what he is talking about.

 

[ianmcd]

We have an issue with the radiators coming on with hot water only. Engineer changed the three port valve. It worked as it should but the same night and since reverted to heating the radiators again. Engineer thinks it may be doing a bypass because non of the radiators have TVRs on and adding them may solve the problem. I’m not sure and don’t want to waste more money if it won’t work. What do you guys think?

Absolute rubbish, why was the valve changed in the first place ?

 

[Deleted member 15266]

because for a long time the radiators were heating up when only hot water was on

 

[fixitflav]

We have an issue with the radiators coming on with hot water only. Engineer changed the three port valve. It worked as it should but the same night and since reverted to heating the radiators again. Engineer thinks it may be doing a bypass because non of the radiators have TVRs on and adding them may solve the problem. I’m not sure and don’t want to waste more money if it won’t work. What do you guys think?

All the radiator return pipes must be commoned before the connection for the HW cylinder return. If not you'll get the symptoms described.

BTW how did you get on with the wire nail test?

 

[Harry Bloomfield]

Engineer thinks it may be doing a bypass because non of the radiators have TVRs on and adding them may solve the problem. I’m not sure and don’t want to waste more money if it won’t work.

That is just a silly suggestion - trying to fix the symptom, rather than the cause.

 

[Deleted member 15266]

All the radiator return pipes must be commoned before the connection for the HW cylinder return. If not you'll get the symptoms described.

BTW how did you get on with the wire nail test?

 

[Deleted member 15266]

Hi I haven’t done it yet as the air seems to be disappearing. I wish we had more experienced heating engineers like yourself

 

[Deleted member 15266]

Oh fixitflav I had him back and when I mentioned hydrogen he said perhaps but the fix would be the same and he wouldn’t advise getting a system clean as the leak is likely under concrete and it’ll make it worse. !

 

[Deleted member 267285]

Are all the radiators heating up with the hot water? Do you have a gravity system? What controls do you have?

 

[fixitflav]

Oh fixitflav I had him back and when I mentioned hydrogen he said perhaps but the fix would be the same and he wouldn’t advise getting a system clean as the leak is likely under concrete and it’ll make it worse. !

I'm wondering about "him"! AFAIK nobody said anything about a system clean.
Still worth doing the nail test to check the water isn't corrosive, to avoid future problems.
On the subject of this thread, unwanted rad heating, see #5. It's been discussed on this forum a few times.

 

[Deleted member 15266]

Tanks in loft. All radiators heating up

 

[fixitflav]

Tanks in loft. All radiators heating up

??? doesn't alter fact that all the radiator return pipes must be commoned before the connection for the HW cylinder return.