Micro bore Pipes

[Mattyeod]

Hi, I've recently moved into a house that has microbore pipes feeding some of the rads, others have 15mm pipes. The heating system is an oil boiler and it seems to be struggling to heat the whole house. some radiators won't go on until others have turned off. I've fitted Hive TRVs to those that I can. I've been told that if I get a gas combi boiler fitted this will solve the issue. My question is has anyone done this and has it solved the issue? Thanks in advance for any help or advice.

 

[CountryFan]

I don’t know what a gas combi would solve the issue, especially if it’s blocked pipework. First port of call would be to try and balance the system.

 

[ChrisJP]

I concur that, if your current oil boiler is heating the CH water OK it's highly unlikley that replacing it with ANY new boiler will somehow free up the water circuit.
Are the radiators than won't go on fed by the microbore pipes?

 

[Mattyeod]

Thanks for your replies, There was an extension put on to the house at some stage in the past (looks like sometime in the 90s) and it seems the new part of the house furthest from the boiler are 15mm pipes which heat up last. The microbore pipes seem to be the ones that heat up first (except 1). I've tried balancing the system but haven't managed to make a difference.

I'm not sure if it's the distance the hot water is travelling:
The boiler is at the far end of the garage
There are 10 radiators
5 double (3 of which are over 2m+)
5 single.

 

[fixitflav]

I don’t know what a gas combi would solve the issue, especially if it’s blocked pipework. First port of call would be to try and balance the system.

Yes, sounds like another case of trying to push a combi

 

[Madrab]

some radiators won't go on until others have turned off.

That's the key point and it basically means your system, in the short term, needs to be balanced. How large is the system, number of rads, average sizes etc?

The biggest screw up that any installer makes IMO is mixing different sized pipework on the branches out to rads. The water will always take the path of least resistance which means the 15mm pipe will always take the majority of the flow until the system is configured correctly.

 

[Mattyeod]

That's the key point and it basically means your system, in the short term, needs to be balanced. How large is the system, number of rads, average sizes etc?

The biggest screw up that any installer makes IMO is mixing different sized pipework on the branches out to rads. The water will always take the path of least resistance which means the 15mm pipe will always take the majority of the flow until the system is configured correctly.

The boiler is at the far end of the house in the attached garage
There are 10 radiators (all 1m+ except the bathroom 600mm)
5 double (3 of which are over 2m+)
5 single.

Thanks, Madrab, it looks like I'll have to get a plumber/heating engineer out to try and configure it properly. As there's a complete mix of 15mm and microbore. Starts 15mm from the boiler then seems to go back to the microbore in some rooms, then 15mm in others.

 

[pcaouolte]

Starts 15mm from the boiler

This is likely to be one of your problems. 15mm isn't big enough to feed 10 rads.

 

[Madrab]

Oh and as others have said, the boiler type has got nothing to do with it.

The boiler is at the far end of the house in the attached garage
There are 10 radiators (all 1m+ except the bathroom 600mm)

Is the property older? If at least half the rads are K2/type 22 and the other are P+/Type 21 and some are over 2m on 15mm/10mm pipe then the system is badly set out.

Even without seeing it, with the best will in the world, that system will struggle regardless of balancing. TBH it should never have ended up like (edit) that.

It may have been the case that it wasn't like that to start with and larger rads were just thrown on by installers that didn't know any better.

I hate to say this but if you want the system to perform the way it should, some re-piping may be needed.