3 port valve problems

[paulie1970]

Yet another problem with a new build system which is as follows,
System boiler with zoned UFH to ground floor and radiator circuit / water tank upstairs.
UFH is controlled by individual room programmers linked to actuators.
Radiators / water tank governed by timer, thermostat, fed by 3 port valve. TRVs on radiators.

The issue is that even with the timer off and the thermostat inactive there is some residual heat (ie not full heat) in the radiators. This can be controlled by closing the TRV's but that defeats the idea of central control and would seem to be wasteful of the boiler.

The electricians swear that all is wired up properly and the 3 port valve is leaking heat into the radiator system despite the timer/stat settings.

Plumber is not convinced.

What are the possibilities of this? Nether plumber nor electrician seem to be making progress despite several visits

 

[Howsie]

Get a plumber who knows now to wire a central heating system otherwise you'll be going back and forth between the pair of them. Get them to own the problem rather than you having to in your spare time.

Unless buggers.

 

[paulie1970]

Ideally would do that but these sub contractors are provided by a main contractor and they need to deliver to complete the build. I feel that it is mostly there now save for these control issues.

Next time I would do it differently but I need to complete this time first.

 

[Howsie]

Then I'd get them to solve it. If you start changing things or suggesting changes if could give them a way out.

Shout at the main contractor and then send them a stinking letter demanding that someone competent resolve your problems.

 

[SmokeyJ]

I would imagine electrics are Ok if it's only partially heating rads. Valve letting by or sticking sounds more likely. Both should be simple for a heating engineer to test...
If it's been an issue since day one, you may be getting reverse circulation and 'gravitating' around heating. This can occur if the return pipework is incorrectly piped.

 

[SmokeyJ]

Does the same pipe to the radiators get hot when heatings on compared to when you are experiencing the issue.
I.e : heating on - flow pipe heats first
Hot water on only - does flow still heat first or is it now the opposite pipe heating first.
If it's the opposite pipe that heats I'd say it's reverse circulation

 

[Jay The Plumber]

check for reverse circulation... what order do the tee's go back into the return and where ?

are you saying that with the boiler off, there is heat getting to the rads ?
if so, could need a check valve on the flow, did an intergas boiler few weeks ago that called for it in the MI's "to prevent gravity siphon"

 

[paulie1970]

Thanks for these thoughts. Heating is not my area TBH.

I will need to check these issues at the weekends with some time to test and review the suggestions. The reverse circulation possibility is a worry to be honest. I only partially comprehend the cause/impact - would it require invasive pipe changes to rectify? Would it constitute negligence in system design or is it not foreseeable?

I will report back....

 

[paulie1970]

check for reverse circulation... what order do the tee's go back into the return and where ?

Can you explain this further please?

 

[tolly]

Can you explain this further please?

The return on the cylinder should be the last tee before it goes back to boiler to avoid reverse circulation when just DHW is called for.

I hope the cylinder is vented and not unvented if its coming off that 3 port valve...post some pictures up if you want.