Would this solve the problem?????

[superknup]

Hi to all.I have a customer who is complaining about a lack of hot water to the bath.They have a combi boiler.There is a 15mm tapping on the boiler for the hot pipe however the hot comes from the boiler in 15mm and then about a foot on has enlarged to a 22mm pipe.This then goes off to feed the bath,basin and kitchen sink.Now am i right in saying that the combi cant cope with the 22mm pipe for the bath,thats why it only runs hot for about 30 seconds,then goes cold?Would changing the pipes diameter from 22mm to 15mm solve the problem?,am i right in saying that you can pipe a bath in 15mm if its from a combi? Any help would be spot on.

 

[offroader]

I had a simular problem at home when I replaced my pipework in my bathroom as I had 22mm going to the bath from the old tank. But now with the combi I used just 15mm and it works fine, with advice from here, although the water is never as hot as it was with the tank feeding it.

 

[ChrisR]

No. All bigger pipe means, is that it'll take a bit longer for the water to arrive.

only runs hot for about 30 seconds,then goes cold?

It's broken!

 

[pierrot]

8) get a heating engineer in your boilers not working properly.

 

[superknup]

Sorry,i forgot to add that the basin and sink are fed in 15mm which is teed off that 22mm pipe and you can run those hot for hours.They dont ever go cold,so am i still assuming that there is a problem with the boiler??

 

[Paul Barker]

You might need to restrict flow into combi so that max flow rate from bath tap is such that temp is satisfactory for running a bath.

If for instance the combi is 24kw you would want to set the flow at 9 litres a minute, 28kw 10 or 11.

If there is still not hot water coming out of the bath tap the combi is underperforming.

You can do more investigation without being corgi registered.

Run the nearest tap for a 24kw combi at 9.7 litres a minute you should get a 35 degrees C temp rise. For a 28kw 10.5. These are rough figures not knowing the boiler. Do this test anyway and then......

Check the gas consumed at the meter over two minutes, find out the output of the boiler and report back, we can let you know if boiler is functioning correctly on hot water with these two pieces of information and advise further.

 

[superknup]

pk,cheers.I'm on the case