Gas Boiler Flow and Return Pipes In Copper?

[tuftythesquirrel]

Hello. I am having a new gas boiler installed in our self build and I am carrying out as much pre-work as I can before the gas safe engineer turns up. The house is all UFH, which is obviously plastic pipe in the screed, as are the supply/return pipes to the 4 manifolds. The boiler is downstairs, with the plant room upstairs. I've run a flow and return in plastic from the hot water cylinders in the plant room down to the boiler. My question is do the connections to the boiler need to be in copper and if so, how long do they have to be before I can change back to plastic. I can’t see anything in the (Wales) building regulations and the Viessmann boiler installation manual has nothing. I have had a quote from a plumber that says he wanted to run 2 metres of copper from the boiler however, I read on the John Guest (Speedfit) site that they recommend 1 metre. Could anyone point me in the direction to where this regulation (if there is one) is written down? Thanks.

[JohnMo]

2 minutes ago, tuftythesquirrel said:

plumber that says he wanted to run 2 metres

The answer is 2m then. He has to certify.

 

Connection to boiler yes copper, I would do all the main connections on the cylinder in copper also.

 

Are you doing proper Viessmann install. With priority demand hot water and weather compensation? So without mixers or additional pumps?

 

If you haven't bought your cylinder, get a heat pump one, with a 3m² coil. Your flow temp will drop and your recovery really quick.

[tuftythesquirrel]

The answer is 2m then. He has to certify. The only paperwork I believe I will get is the gas safety record, which relates to the boiler and flue installation rather than the pipework. The pipework manufactures documents say a minimum of 1 meter. That’s why I wanted to see it written in a regulation somehow, rather than someone’s opinion. Unfortunately, on that quote he proposed a 40kW boiler and I’ve fitted an 11kW, since the house heat loss is only 4kW, hence I wasn’t completely convinced by his competency.

 

Connection to boiler yes copper, I would do all the main connections on the cylinder in copper also. In an ideal world I would but you haven’t seen my pipe run😁, so I will probably stay with plastic.

 

Are you doing proper Viessmann install. With priority demand hot water and weather compensation? So without mixers or additional pumps? Yes, PDHW and WC, but not a standard install. It’s a 100-W system boiler and I’m using the Viessmann Plusbus EM-EA1 interface to control the burner and implement the WC using an Idratek automation system via a 0-10V signal. When I bought the manifolds and they came with mixers and pumps and I wasn’t convinced I didn’t need them. However, now I’ve accumulated a bit more knowledge and experience, I suspect they might be removed in the future.   

 

If you haven't bought your cylinder, get a heat pump one, with a 3m² coil. Your flow temp will drop and your recovery really quick. Yes, good point, I have.

 

Thanks.

[JohnMo]

Making it complicated instead of simple. Been there got the tee shirt, paid the super high bills. Then went to boiler controlling everything halved my gas bills.

[Peaklander]

On 17/09/2024 at 15:00, JohnMo said:

Making it complicated instead of simple. Been there got the tee shirt, paid the super high bills. Then went to boiler controlling everything halved my gas bills.

 

Hi, I don't frequent this forum often enough but visits are getting more frequent. So forgive the question but can you point me to more detail about what you said? Thanks

[marshian]

On 17/09/2024 at 15:00, JohnMo said:

Making it complicated instead of simple. Been there got the tee shirt, paid the super high bills. Then went to boiler controlling everything halved my gas bills.

 

Made me chuckle reading that - I'm still getting closer to the advice given by yourself now 5 out of 13 rads/rooms are now running pure weather compensated flow temps with no TRV influence

 

OP - Bearing in mind the Viessmann boiler on PDHW will throw everything it can at the HW cyl (so 80 deg HW) I think I'd be running copper to and from the cyl - Low temp CH circuits plastic would be fine but I'd do copper for the Hot loop