No flow through rads

[david3456]

My daughters ch has been lacking output for some time. On first inspection the boiler return was taking along time to warm up. Although the pump was making all the right noises we speculatively changed it. No difference.

So we then flushed the system with mains water. After putting it all back, good temperatures now appear on both sides of the boiler on hw and bypass.

The rads are more of a mystery. When we began to flush them there was no flow until we realised the TRVs were all directional and so changed flow direction. Going round each rad individually, all subsequently gave good flow.

Back in the complete system, with rads only, the return temp still shows no flow. From the flush and from what little heat gets through we know that system flow is the correct direction.

The 3 port valve appears not stuck because the hw side correctly goes cold when demand changes.

Do directional TRVs need a minimum pressure? Can a 3pv fail in such a way that the rad side can be permanently shut even though hw side switches properly? (The 3pv was taken off to flush but while off we didn't make the system live to eyeball the innards.) Any other possibilities to consider?

 

[Agile]

It seems to me that you have a very simple fault.

Unfortunately without having seen the system, I cannot guess what it is from what you have said. Not being told the boiler model does not help either.

Is the auto (?) bypass stuck open?

You seem to have preferred to do a lot of DIY guessed at fixes rather than calling an engineer.

I suspect that you are going to need that engineer!

Tony

 

[david3456]

It seems to me that you have a very simple fault.

Indeed. There is no flow through the rads. There can only be a finite number of avenues to go down.

Unfortunately without having seen the system, I cannot guess what it is from what you have said. Not being told the boiler model does not help either.

You don't need to guess a solution. I am looking for possibilities. (And if you insist, I can prove the boiler is not part of the problem.)

Oh, by the way, if an auto bypass (it isn't) sticks open the boiler return temperature rises, not falls.

 

[D_Hailsham]

When we began to flush them there was no flow until we realised the TRVs were all directional and so changed flow direction.

Did you remove the TRV heads before flushing?

Have the TRVs been installed the correct way round?

There will be an arrow on the body; this shows the direction of flow. The TRV must be fitted so the arrow points towards the rad on the flow (hotter) pipe and away from the rad on the return (cooler) pipe. This means that the TRV head will be vertical at one end and horizontal at the other end.

 

[ianmcd]

A TRV fitted the wrong way round will not cause any problems untill it tries to shut down and will not cause flow restrictions only problem if they are wrong way round is they might get noisy when satisfied and trying to close

 

[bolshy]

Considering you seem to think you know more about heating than Tony, (which most of us don't) what brought you to the huge assumption that your 3 port is working correctly?

 

[david3456]

When we began to flush them there was no flow until we realised the TRVs were all directional and so changed flow direction.

Did you remove the TRV heads before flushing?

Have the TRVs been installed the correct way round?

Yes, I did say that we had good flow through each radiator once we realised they are directional and that they are the right way round.
Do they need a minimum pressure to operate?

 

[ianmcd]

IT HAS NOTHING TO DO WITH YOUR TRVs !!!!!!!!!

 

[david3456]

Considering you seem to think you know more about heating than Tony, (which most of us don't) what brought you to the huge assumption that your 3 port is working correctly?

I asked a specific question about 3pvs. Have you got anything to contribute or are you just intentionally wasting bandwidth?

(Why is that everytime someone posts something on this forum it starts an inquisition? It's only a central heating system, not quantum physics.)

 

[david3456]

IT HAS NOTHING TO DO WITH YOUR TRVs !!!!!!!!!

At last, the first positive contribution. Thanks.

 

[NiallEvans87]

Are you a master of quantum physics as well as central heating then?

 

[ianmcd]

IT HAS NOTHING TO DO WITH YOUR TRVs !!!!!!!!!

At last, the first positive contribution. Thanks.

think of it laterally a TRV shuts down a radiator when the room has reached the temperature that the user has set on the TRV so say setting 3 on the TRV is 15 C then once the ROOM reaches 15C then the valve will stop the water supplied from your boiler from going to the radiator so the room will not get any hotter, if the room is below the desired temperature the TRV cannot stop the rad from getting hot regardless of which way round it is installed

 

[david3456]

Are you a master of quantum physics as well as central heating then?

No. But I expect that if I went to a forum on quantum physics, responses would be more informative.

 

[ianmcd]

Are you a master of quantum physics as well as central heating then?

Nope but I have been a heating engineer for 35 years and have forgotten more about heating systems than you will ever know , so stick to Quantum physics Mr Evans

 

[bolshy]

I asked a specific question about 3pvs. Have you got anything to contribute or are you just intentionally wasting bandwidth?

(Why is that everytime someone posts something on this forum it starts an inquisition? It's only a central heating system, not quantum physics.)

Your know-it-all attitude and arrogance are astounding considering you have come to the forum for advice. Concerning a heating system YOU can't seem to diagnose or fix. Without help.

And you won't be receiving any more of mine, you obnoxious little man.....