32 main pipe instead if 22 (or 25)

[na100681]

Hello,

My heat pump engineer asked me to change the main to 32mm pipe, I think I have a 22 or 25 at the moment. I made a quote with Thames water and it will cost me around 3500 pounds to do it. My question is do I need to do it? I have 4 bathrooms on 4 different levels.

If yes, there will be 32 pipe on the main but what will be inside do I still keep the 32 for all my output : shower, sink...or do the pipes go smaller? What will be best for pressure and flow?

Thanks for your help, I'm completely unknowledgeable on this.

Nadia

 

[Deleted member 267285]

Have you asked your heat pump engineer why you need it? I’m clueless with heat pumps myself and their maybe a genuine reason for it, but if you’ve not asked them for a reason, then others on here might not be able to advise.

 

[na100681]

Have you asked your heat pump engineer why you need it? I’m clueless with heat pumps myself and their maybe a genuine reason for it, but if you’ve not asked them for a reason, then others on here might not be able to advise.

No I didn't. The guy is also doing my underfloor heating so it might be because of the underfloor heating so the flow is better on the pipes

 

[Madrab]

OK, the size of the mains will have no impact on the central heating.

Increasing the mains diameter will increase the flow of water into the property. To benefit from that then the internal pipework would need to up to at least 22mm to the branch points for each of the rooms that use it. That and it will increase the flow of any unvented HW system, if one is installed. As suggested, not sure why you can't ask him to explain why he recommends going to 32mm though?

I would hazard a guess that it's more to do with feeding 4 bathrooms and utilities and possibly an unvented HW cylinder all at the same time, dynamic mains pressure not withstanding. Is he having anything to do with the hot and cold services in the property?

 

[na100681]

Thanks Madrab for your reply. Yes we are going for invented HW cylinder so it might be worth going this way just to avoid any risks when all the bathrooms are used at the same time + UFH. I didn't understand the last question, can you explain please? Also, is it better to have 2 circuits one for the UFH and one for the bathrooms...?

 

[Madrab]

UFH has nothing to do with the mains cold and hot and water supplies, it is underfloor heating which is part of the central heating/heat pump and once that is sealed, it does not interact with the hot and cold water.

If you are thinking about installing an unvented HW cylinder along with feeding 4 bathrooms with mains cold as well as the hot water then maximising the flow by using a 32mm mains pipe may not be a bad idea but that depends on how the mains water pressure and flow are at the moment

The last question was, is the heat pump chap also working on the hot, cold and unvented water supplies?

 

[na100681]

Sorry I made a mistake we are not having an invented HW but a traditional hot water tank that goes with the heat pump + underfloor heating water system with 16mm pipes on all the floors. We also will put a softener in all the system (4 bathrooms) but the sink in the kitchen. What size do you think I need to have all this works if my main is 32mm? Thanks again for your help and sorry for the mistake!

 

[JohnD]

Sorry I made a mistake we are not having an invented HW but a traditional hot water tank

Do you mean a hot water cylinder that is fed from a cold water tank in the loft? Rather unusual these days unless you have a hotel or gym or something.

 

[Deleted member 267285]

Do you mean a hot water cylinder that is fed from a cold water tank in the loft? Rather unusual these days unless you have a hotel or gym or something.

Not really, my house was built and completed in 2010 and we have that setup.

 

[JohnD]

So do I, but if I was having the plumbing renovated, I would probably go for an unvented.

 

[na100681]

Do you mean a hot water cylinder that is fed from a cold water tank in the loft? Rather unusual these days unless you have a hotel or gym or something.

No just a tank water near the heat pump on the ground floor

 

[na100681]

So do I, but if I was having the plumbing renovated, I would probably go for an unvented.

Does an invented works with a heat pump?

 

[JohnD]

No just a tank water near the heat pump on the ground floor

Don't understand.

 

[Madrab]

invented

Unvented not invented.

No just a tank water near the heat pump on the ground floor

That wouldn't be to supply the hot water cylinder, if so then it's a real design problem. Usually if you have an open vented hot water then you would have a 50Gal cistern in the attic. If you do have a gravity system then it will struggle to supply 4 bathrooms with anything more than low flow if several are being used at once. I think there may be a bit of confusion here over what it is you are getting/installing which makes our ability to advise really difficult.

That and the cold water/hot water setup has nothing to do with the UFH so it wouldn't really be mentioned in the same subject. The heat pump will send warm water to the hot water cylinder to heat the water up and warm the UFH but that's the only real interaction between all three.