New plumbing & heating system advice

tommyh311 · Jul 7, 2024

Hello,

I'm installing a new central heating & plumbing system and just wanted to run through my design choices to make sure I haven't overlooked anything! It's a 2 bed, 1 bathroom semi-detached house.

These are the proposed appliances: WC, Basin, Bath, Shower, Bath, Washing Machine, Kitchen Sink, Dishwasher.

I'm looking to put in a 30kW combi boiler. The cold mains pressure is around 3 bar with 13 l/min flow rate. The cold main comes into the house at 15mm. I'll run the cold and hot pipes in 15mm to the above appliances.

Central heating wise, I'll run the main flow and return pipework in 22mm and branch off in 15mm to radiators.

Does this sound reasonable?

Any guidance is very much appreciated,

Thanks,

Tommy

ShaunCorbs · Jul 7, 2024

Have you calculated the Heatloss in regards to part l eg max flow temp of 55c ?

tommyh311 · Jul 7, 2024

Hi Shaun,

Yes i've oversized rads to allow for this.

Thanks,

Tommy

ShaunCorbs · Jul 7, 2024

tommyh311 said:
Hi Shaun,

Yes i've oversized rads to allow for this.

Thanks,

Tommy

And converted the figures from the stock listed output to dt24 eg conversion figure of 0.385

Eg 1000w stock listed output would only output 385w at dt24

tommyh311 · Jul 7, 2024

Yes I've accounted for dt24,

Thanks,

Tommy

ShaunCorbs · Jul 7, 2024

All sounds good then 15mm copper for each rad max of 2.5kw main run calculated for a max of 6kw eg 22mm copper

tommyh311 · Jul 7, 2024

Great thanks Shaun,

Tommy

Jerry · Jul 17, 2024

30kw for a 2 bed? Easily enough to heat the house.

The large KW output of a combi is for the volume of hot water produced. The bigger the combi, the more DHW you get......People like big hot showers

Yes yes yes. Heat loss calcs etc etc

The lowest output I could quickly find for a combi is 24kw. Call each rad about 2kw and that's about 12 rads. Combi's are usually only fitted in a 1 bathroom property and don't usually have more than 3 bedrooms.

Yes yes yes I know. So much wrong here and so many generalisations. I would size a system/open boiler to the property but not so much a combi.

Now, how much grief am I going to get??

tommyh311 · Jul 17, 2024

Hi Jerry,

Thanks for the reply. It's only a 1 bathroom property so a combi will be fine. I didn't mean to write "Bath" twice in my appliance list!

Thanks,

Tommy

Jerry · Jul 17, 2024

Looking at how you replied to ShaunCorb's questions, I am sure you will nail this.

New plumbing & heating system advice

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