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.

 

[paulie1970]

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.

Sure. For what it is worth here are pictures. Hopefully it makes sense to someone....

 

[Chalked]

It will never work properly with a three port. There is always a way through the valve. It should be done with multiple two port valves.
One for cyl, one for rads and one for underfloor .

 

[Chalked]

Oh dear! Overflow on prv discharge.
Back to main prob.
Cylinder stat will turn off three way and two way valve ( lazy buggers for not replacing three way) three way shuts hot water port, underfloor calls and water goes round heating circuit too.

Just replace the three port with one zone valve on the heating.
Oh and advise they get a G3 engineer to sort the cylinder.

 

[paulie1970]

Oh dear! Overflow on prv discharge.
Back to main prob.
Cylinder stat will turn off three way and two way valve ( lazy buggers for not replacing three way) three way shuts hot water port, underfloor calls and water goes round heating circuit too.

Just replace the three port with one zone valve on the heating.
Oh and advise they get a G3 engineer to sort the cylinder.

Thank you for the thoughts on the system engineering. There may well be a correlation with the UFH and rad heat. I will monitor this

What is G3 non-compliant about the system that you can see?

 

[paulie1970]

It will never work properly with a three port. There is always a way through the valve. It should be done with multiple two port valves.
One for cyl, one for rads and one for underfloor .

Many thanks. Does this suggest reverse circulation or simply poor control? Would the three port save effort installing at expense of fine control? The pumber initially thought everything would be controlled via TRV and did not supply thermostat. Presumably it would "work" under such circumstances but not well?

 

[Riley]

Not a great install. Would doubt installer was G3

 

[paulie1970]

Not a great install. Would doubt installer was G3

Possibly not, I didn't have a choice. Is the system non-compliant or just not best practice? In any event it doesn't work...

 

[Riley]

It's really a different issue. Without going into too much depth the safety discharges on the cylinder are not piped correctly. It's actually illegal for a non-G3 engineer to work on one of these cylinders. And you always have a choice. The installers should be upfront with their qualifications.

 

[paulie1970]

Deal came as part of a package under a main contractor. I had assumed that he would be diligent in selecting sub contractor. The subbie may indeed be G3, it wasn't my concern. My main interest is in getting it working rather than detecting and punishing possible illegality. There would seem to be some pointers on how to proceed here...
Thanks

 

[Riley]

Ok that's your perogitive however when these things aren't plumbed in properly it sets alarm bells ringing. Not to sound too drama queen but unvented cylinders are literally a bomb which can take out your roof/house wall if they aren't installed correctly. I'm not necessarily saying to raise the illegality but rather concerns about yours and your families safety. Up to you though if course

 

[paulie1970]

Ok that's your perogitive however when these things aren't plumbed in properly it sets alarm bells ringing. Not to sound too drama queen but unvented cylinders are literally a bomb which can take out your roof/house wall if they aren't installed correctly. I'm not necessarily saying to raise the illegality but rather concerns about yours and your families safety. Up to you though if course

Sorry, my response wasn't meant to be dismissive of your suggestion. Beyond fixing the 3 port issue of course safety is of concern. Will probably get it reviewed by a third party expert given that it raises concerns with experienced engineers on this forum. If unsafe then it should be rectified.

 

[Jay The Plumber]

it wont work right until its put right bud.. we cant help you one here anymore than we already have.. you do need to get a fella in.

 

[Howsie]

Personally I'd tell them you're getting someone in who knows what they are doing and you'll send them the bill. It's a waste of time otherwise.

 

[walterwhite]

And if the installer wasn't G3 you won't get the building regs certificate....you'll need that in the event of an insurance claim or when you sell the property

 

[paulie1970]

An update on the 3 port valve after having a spare 5 mins to investigate. It is a 3-port 3-position valve, Honeywell V4073A. I think that perhaps means that it can be in a closed position, with no flow to cylinder or rads?

In that case the system may be OK from an architecture perspective. I'm fairly sure the installer would be qualified otherwise they wouldn't have accepted the job, knowing that they couldn't gain sign-off.

Perhaps back to electrical connectivity?

Irrespective, hopefully both disciplines will get together soon to resolve.