Should my 3 port valve be a 2 port valve?

[coup27]

Hi,

I bought a house last (built 1988) which had a 3 port valve (Honeywell V4073A), a vented cylinder and 2x tanks in the loft. I had a plumbing company remove the cylinder, 2x tanks and replace it with an pressurised cylinder and filling loop along with new radiators. They chose to keep the existing 3 port valve. That company never actually came back and finished off so I had to get the plumbing company who did my bathrooms to commission and fire up the system. I asked them to check the work done and they never commented on the valve being incorrect.

I've now chosen to have a Honeywell Evohome installed and the person who I found on the Honeywell approved installers list came out and said my value should have been changed to a 2 port valve for safety reasons. He said a 2 port valve is actually supplied with the new cylinder and my first plumber should have fit it. He's given me a quote to install the Evohome but also to supply and fit a new 2 port valve.

Can somebody please help me on which is correct?

Thanks.

 

[ShaunCorbs]

Yes you need to fit a 2 port in either s plan set up or after the 3 port (which is silly in my opinion)

But definitely need a 2 port on the cylinder flow

And also your cylinder needs checking By a G3 engy and registering with building control

 

[coup27]

Hi,

Thanks for your reply. Could you expand more on this please:

"And also your cylinder needs checking By a G3 engy and registering with building control"

 

[ShaunCorbs]

If a 2 port wasn't installed what else is wrong best to get it check out by a unvented tech (G3 qualified) and I doubt they have registered it with building control which is a requirement

 

[coup27]

Thanks. I'll look into that. Can I find out myself if my cylinder has been registered with building control?

 

[ShaunCorbs]

Thanks. I'll look into that. Can I find out myself if my cylinder has been registered with building control?

You could phone them up, they should have a record

Also is the benchmark filled in normally in the back of the instructions also it's normally duplicated on the cylinder in short

 

[coup27]

As the first plumber never commissioned the system but the second company did, I suspect neither have filed any paperwork.

I have just located my first plumber on the gas safe register and he does not have a tick for unvented cylinder work. Does this mean he should not have installed it? I cannot find the second company on there.

I was given no paperwork from the first plumber. No instructions for the cylinder and there is nothing on the cylinder.

 

[ShaunCorbs]

Correct he should not have fitted it if he's not G3 registered, but not all G3 engys are listed on gas safe as you have to send them your qualifications I would phone him up and ask him straight are you G3 registered also what is your reg number

That's a problem I would get someone out to check everything is safe and working correctly

 

[coup27]

To be honest I would rather not ring him. Is there a central body who manage the G3 certification who I can check myself?

Back to getting my Evohome installed, on the Honeywell website it lists many approved plumbers for installing the system but as some of the work is electrical are they still OK to do that? There aren't many plumbing and electrical companies out there.

What I think I need is somebody who is G3 and Honeywell certified to come out and install my Evohome and inspect my cylinder. Fortunately I am not in the house at the moment so all the heating and hot water is off.

 

[ShaunCorbs]

yes building control if its been registered

 

[coup27]

Thanks for your help.

 

[fixitflav]

Hi,

I bought a house last (built 1988) which had a 3 port valve (Honeywell V4073A), a vented cylinder and 2x tanks in the loft. I had a plumbing company remove the cylinder, 2x tanks and replace it with an pressurised cylinder and filling loop along with new radiators. They chose to keep the existing 3 port valve. That company never actually came back and finished off so I had to get the plumbing company who did my bathrooms to commission and fire up the system. I asked them to check the work done and they never commented on the valve being incorrect.

I've now chosen to have a Honeywell Evohome installed and the person who I found on the Honeywell approved installers list came out and said my value should have been changed to a 2 port valve for safety reasons. He said a 2 port valve is actually supplied with the new cylinder and my first plumber should have fit it. He's given me a quote to install the Evohome but also to supply and fit a new 2 port valve.

Can somebody please help me on which is correct?

Thanks.

I'm curious about why you want to change from Honeywell Y-plan (using the V4073A mid-position valve). The fact that the cylinder is now unvented makes no difference to the boiler side of the heat-exchanger. If it worked before, all that needed changing was the cylinder and any necessary pipework mods.
With the S-plan you need two 2-port valves.

 

[Stoney Ground]

It needs it as the unvented cylinder requires a 2 port valve, which is wired through the cylinder and overheat Stat.

 

[fixitflav]

It needs it as the unvented cylinder requires a 2 port valve, which is wired through the cylinder and overheat Stat.

I can see that if you change from Y-plan to S-plan you need two 2-port valves instead of one 3-port. I don't see why the change from Y-plan was made. Either system takes input from the cylinder stat, among other controls.
Do you mean the boiler overheat stat? That's needed irrespective of the control system. Or is there another overheat stat somewhere?

 

[snowhead]

Or is there another overheat stat somewhere?

Yes, in the Unvented.

 

[fixitflav]

Yes, in the Unvented.

OK, but would S-plan be different from Y-plan in that respect?
Also, I'd assumed that expansion from the (unvented) cylinder would go back up the mains feed. If it can't (eg if there is a NRV on the feed line) some protection against pressure build-up is clearly required, but from any temperature rise, not just an overheat condition.
Sorry if my questions are naïve, I'm just a DIYer!

 

[Vee]

That's why its a job for a competent person. Expansion is usually provided by way of integral expansion gap or external vessel depending on manufacturer, not expansion into the water main. The 2-port valve is provided by the cylinder manufacturer too and its clearly stated in the instructions that it is required to be fitted irrespective of whether it's Y or S-Plan. The unregistered and incompetent first plumber most likely bagged that for himself not understanding it's purpose.

 

[coup27]

The 2-port valve is provided by the cylinder manufacturer too and its clearly stated in the instructions that it is required to be fitted irrespective of whether it's Y or S-Plan. The unregistered and incompetent first plumber most likely bagged that for himself not understanding it's purpose.

Correct. Despite what transpired I there is no evidence that the first plumber does not have a G3 ticket. I have discovered that there is no central body which maintains G3 certification. Each plumber has their own "competent person scheme" and if you know which scheme they use you can verify their qualification but the only way to know which scheme they use is to ask them.

The guy I found on the Honeywell website who does have a G3 ticket fitted a 2 port valve for the cylinder for this safety feature. During commissioning when the heating only was on the hot water was heating up and vice versa. He advised me that the original 3 port valve which was now ~30 years old was showing signs of wear inside and is not making a tight seal anymore. I had him back to replace the 3 port valve with another 2 port and convert to S plan as replacing the 3 port with a like for like would be silly in his opinion.

Another error which has been discovered since my last post by the 3rd plumber is the stat which was fitted to the cylinder was the wrong one. The cylinder was supplied with a digital stat suitable for S plan setups. My house at the time was Y plan but this was only picked up by the 3rd plumber. Prior to that my hot water would never switch off once it had reached temperature and it was down to the incorrect stat.

Regarding certification, the current plumber has visually looked over the system and doesn't see any major errors. There are a couple of minor ones which may get snagged but he said to fix them are not expensive. I have spoken to my local building control and they will come out and inspect and sign off etc for £300 which is something I'll have done in January.

I would say there is a moral to all this but I can't find one. A lay person could never have known that there is a separate G3 qualification for unvented cylinder work and the lack of a central body and with it being optional to display on the Gas Safe website the customer has no chance.