Rads getting hot when hw is called

[collyplumb]

So same old story.
Vented system with a 3-port valve. (x2 new)
All rads including the towel rails are on the CH flow. I moved the T/R in the bathroom and problem started.
so I thought, of course, I looped it and there is reverse circulation??
this is what i have done to try find the problem
- cut out my work and put stoppers in as the flow and return comes off the loop.
- replaced 3-port valve
- put stop-cock in after 3-port valve on CH to ensure it is not leeting water through.
- powerflush-just for luck
no change yet.
as my work was cut out and the valve replaced and a stop-cock put in, I figured maybe it was work someone else had done so i turned off all rads(lock shield and TRV) and set on HW call.
drained all the water out of the CH flow untill I could blow air through from the 3-port valve to the drain cock below. No more water came out and HW circulation was still on. no luck when i filled it all up again.

If anybody is still reading I appreciate the attention. any ideas

 

[ChrisR]

Pump in backwards??

 

[collyplumb]

Thanks re. reply

No pump still in its original pos. grunfos working like a trooper

 

[gas4you]

Any chance there is a manual bypass (gate valve) fitted and could be piped up incorrectly?

 

[collyplumb]

There is a bypass. water flows through the pump, into a T which diverts the water to the bypass and 3-port valve. from the T the bypass connects back into the return as the heating coil comes out the tank. Tried it shut and open yet same prob.

 

[gas4you]

Are/were the towel rails on an old part of the heating system that was on the original gravity primary circuit (if it was one) and could now be 'looping' the flow through them and the rads?

 

[sambotc]

Any chance you've wired/fitted the 3 port in wrong way round? heating hot water wise?

 

[collyplumb]

The T/Rs were all on the CH flow. still are. except for the on that i moved that i have no capped. thanks

 

[collyplumb]

No that ones ticked off as well. got it in right way up. thanks

 

[gas4you]

Any chance you've wired/fitted the 3 port in wrong way round? heating hot water wise?

I did this last week. Too much yapping to the customer whilst workin At least I noticed and changed it around before he noticed and I left

 

[sambotc]

Easy done!

So let me get this right, do you know if this problem was present before you started work? Customer told you anything?

Failing that, if you've basically reverted the system back to its orignal design, the only thing i can think of it being is the 3 port?

Is it definatly a 2 pipe system?

Sam

 

[collyplumb]

Thanks sam. yip 2 pipe system. client says all good before, easy to believe as its in a secure complex.. all houses are the same and we have done work in other houses and not had similar problems. just stumped

 

[gas4you]

When you say rads are getting hot, do you mean really hot or just warm?

 

[sambotc]

If you haven't changed anything else pipework wise then you can't have altered it's design. Have you definatly got the right replacement 3 port valve for what you replaced?

Has to be a wiring or mechanical fault doesn't it, nothing else has changed especially if you have powerflushed, which would rule out any blockage/obstruction??

Sam

 

[collyplumb]

hot as. when they still cold and open them with the HW calling the heat is coming from the reverse side (lock-shield as appose to TRV)