New Central Heating System

[CDH11]

We've recently built a new 2 bedroom extension and are now needing to fit the radiators and are also going to have a new Worcester Bosch 34 CDI boiler installed.

We've had a few people down for some quotes, but they seem to have different ways of doing the job and so we're just a bit confused as to what would be the best option.

It's now a medium sized 5 bedroom detached house and all the original central heating pipe work is done in 15mm copper. The pipe was 22mm until where it branched off for upstairs and downstairs. All up stairs was then on 15mm to the 4 radiators and all downstairs was again on 15mm to another 4 radiators. A couple of guys that have come down to quote for the job were surprised that it was all done in 15mm and said it should have been 22mm until where it reached each radiator and then branched off to 15mm. The last guy that came down said that the original pipe work all in 15mm was OK.

Can anyone advise on this as confused on which one to go with?

 

[Ermintrude]

How many bathrooms? I wouldn't ever recommend a Worcester combi.

 

[Ray Stafford]

Its hard to say without seeing it. If the radiators used to get hot, and you had a warm house, then I guess it worked! Whether it will still be ok after the extension is the tricky part, and cannot be determined over the internet!

As regards the boiler choice, if you get 10 answers here, they will recommend 11 different boiler types.

A better approach is to find a gas-safe registered engineer who you trust, preferably by word-of-mouth recommendation, and take their advice. What part of the country are you in? Maybe one of the forum regulars is near you?

 

[TBServices]

Sounds like you've chosen the boiler yourself. First mistake.

Personally I think if the system is piped up wrong, which it is, you may aswell start completely from new, and zone as required.

The last guy is wrong. Told you what he thought you'd want to hear. Don't have him back.

 

[AWheating]

as you can imagine a certain sized pipe can supply a certain amount of heat along a certain length of pipe with a certain resistance with a certain amount of noise.

so knowing the pipework is correct is hard to say

most plumbers work on experience when running heating pipework. I would expect to see 22mm running 3 or more radiators as a general rule of thumb on a standard install in a standard house.

to me its sounds like it would be worth repiping the system, zoning it to suit the properties use, flushing out well anything kept from the existing system and stick a good magnetic filter on with a few bottles of inhibitor.

post your location, there maybe an engineer on the forum near you that could come and quote the work and give advise.