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Plumbing

What size pipework

Anonymous user 15/03/2024 - 2.56 PM

I’ve had a new Combi boiler installed. Previous boiler was a conventional system. the new boiler has been installed to all the existing pipework. Coming From the DHW from the Combi is 15mm But then steps up to 22mm underneath the floor boards then supplies bathroom and kitchen. I’m having a new bathroom installed soon with the bath having a thermostatic bath/shower mixer tap attached to the bath. Will having the pipework in 22mm affect the performance of my shower? I’ve been without a bathroom ever since the boiler was installed but I have noticed in the kitchen the delivery of hot water is rather slow. Could this be down to the pipework being in 22mm and having a bigger volume of water to pass through before the hw reaches location? I understand this is normal for a Combi but thought it may be a little quicker. So if the dhw pipework was all in 15mm to all outlets - kitchen sink, bathroom basin and bath would I get ultimate performance from my boiler? Or am I overthinking?

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3 Answers

Anonymous user

Ultimately it comes down to the size of your Combi boiler ( in KW ) IF your boiler size is big enough it shouldn’t cause too much of a problem. But... Ideally all of your hot water pipe work should be in 15mm. Simply put the bigger the KW the more litres of hot water it will produce per minute. This is where the boiler installer should have prompted you to go for the biggest size Combi that your budget would allow. As for the pipe sizing issue, this is one of the downsides of replacing a conventional cylinder with a Combi boiler. Will it work as it is? YES it will work but you may have to turn your hot water tap on then close it slightly to slow the flow rate down to get the water to a “hot” temperature. If you whack it open full bore you may just get Luke warm water. This Comes back to, pipe size increase from 15 - 22 and the Kw size of your boiler.

Answered26 May 2020

Oldfield Plumbing & Heating ltd

Rating: 5 out of 5

Rochester

22mm is a better performance. But it’s down to the size of the boiler

Answered24 May 2020

Anonymous user

Size of the boiler is important however, it is not everything. You'd need to consider two main issues. 1) What is your incoming supply volume 2) What is the requirement either from your taps or shower both considerations are in the respect of how many litres per minute you have coming in, and what you need coming out. Once you've determined this, you'd be able to consider if your boiler is large enough and or whether it's adequate but you need to increase the capacity within the property. There are a number of things that can be done to increase it should it be required.

Answered26 May 2020