Effect of replacing 22mm copper with 15 plastic

[MrGatch]

Thanks for all of the replies.

Builder has agreed to replace the 5m stretch in 22mm copper with push-fit joints which I'm happy with. This is after a conversation with the heating engineer!

how many rads do you have totally ish?

also sounds like you need to size the pump correctly to pump the water up 3 floors etc

Looking at 13 rads of various sizes over 3 floors - mostly horribly old ones. That's existing, plus about 50m² of new UFH. Heating engineer thinks that a Vaillant ecoTec Plus 637 is sufficient for that based on a walk around the house and review of the UFH plans.

He's also proposed a Super Oso 250L for the cylinder.

Not entirely sure what he is proposing pump wise. Would more than the pump in the boiler be required do you think?

 

[Riley]

What floor is the boiler going on? Kw wise you should be ok. As I think was mentioned previously it might be better and more effective to pump each zone

 

[MrGatch]

What floor is the boiler going on? Kw wise you should be ok. As I think was mentioned previously it might be better and more effective to pump each zone

Currently the old 37kW combi is in the cellar and manages to pump up to the second floor with the internal pump. No external pumps or expansion vessels.

The new system boiler (and cylinder) will be a floor up on the ground floor which I assume should help with pressure drops and pump effort.

Will talk with the heating engineer about what he's thinking with the the zones. If zone pumps are in the mix, would that mean the pump in the boiler is just supplying the cylinder?

 

[ShaunCorbs]

Your looking at needing around 18l of expansion

Also he should do a heat loss calculation as the cylinder will take around 15kw

 

[Riley]

Has the heating engineer done anything?

 

[MrGatch]

Has the heating engineer done anything?

Not really. He's walked round the house and kicked a few tyres.

I've suggested most of the stuff regarding new water main, new boiler location, moving from combi to cylinder.

I chose the EcoTec+ 637 and he confirmed that its up for the job and suggested the Super Oso 250L.

I completely trust his professional opinion ( assume he's told the builder he needs to replace the 22mm copper yesterday), I've just not seen much of him. My interface is with the builder.

When I see him I'll mention if he's planning two use two external pumps for the zones. He did mention that I could use a low-loss header but it might be overkill. He also suggested it would be expensive!

 

[ShaunCorbs]

so basically he's done nothing and the builder has done the plumbing

 

[MrGatch]

so basically he's done nothing and the builder has done the plumbing

Pretty much! A red carpet is being rolled out for him to turn up to connect up the boiler, cylinder, UFH and my new gas supply.

The builder is doing the rest - he's been pretty open about that as its to keep costs down.

I suppose the the downside of that is that it cost less in general but then random costs extra when they make mistakes that I pick up on.

I've painted them in a really bad light, but they are a great dedicated bunch. They just aren't experts in plumber/heating.

 

[ShaunCorbs]

That's the thing we have a lot of these builder doing the plumbing not many end up without problems / the systems don't work etc

My advice get the builder to do the building work and the gas safe engy / heating engy to do the pipework and heating etc

 

[Riley]

I am sorry to say it but I think you are asking for trouble if you let the builder do all the plumbing work. If they are talking about hanging the boiler etc then I would tell them you want a new gas safe engineer and for them to do all of the wet and gas. It is not worth you saving a couple of quid for the potential headache this could cause you in what is quite a major upheaval in your home. The fact that you say they aren’t experts in plumbing and heating set all kinds of alarm bells ringing with me have you checked their insurance coverage etc it’s just not worth it its your home after all