Microbore pipe - complete garbage?

[Tom079555]

I moved into a house where the heating system used microbore pipes. The radiators were tiny, and I suspect the job was done by the previous owner as a DIY job. The house does not heat properly.

I have bought larger radiators and spoke to a few plumbers - but nobody seems to want to job.

1 chap said the microbore pipe should be taken back to 15mm pipe in order to supply larger radiators downstairs.

He also said that if 1 large radiator is fed from microbore pipe, this cannot then be extended to supply another large radiator in the next room because it will just 'skip it', and not heat up.

The 2nd plumber said he would just connect both large radiators to the microbore and it would be fine

Someone is fibbing - but neither ended up wanting the job.

Who was fibbing?

 

[Doug99]

I have a 4 bedroom house with microbore CH and Worcester combi.
The only issue I have experienced is a 'boiler engineer' recommended a full system flush last year which then blocked up my boiler.
I now know that flushes should only be conducted on individual rads for microbore systems.
It was a pain at the time, but has now been sorted and the CH now runs efficiently.

 

[Johntheo5]

I moved into a house where the heating system used microbore pipes. The radiators were tiny, and I suspect the job was done by the previous owner as a DIY job. The house does not heat properly.

I have bought larger radiators and spoke to a few plumbers - but nobody seems to want to job.

1 chap said the microbore pipe should be taken back to 15mm pipe in order to supply larger radiators downstairs.

He also said that if 1 large radiator is fed from microbore pipe, this cannot then be extended to supply another large radiator in the next room because it will just 'skip it', and not heat up.

The 2nd plumber said he would just connect both large radiators to the microbore and it would be fine

Someone is fibbing - but neither ended up wanting the job.

Who was fibbing?

Do you know what size microbore, is it 10mm or 8mm?

 

[Elsa TLC]

My rules using microbore is that each 10mm feed comes off a 22mm flow & return.
15mm is possible depending on how the system has been piped up.

The fella that said he would do 2 large rads with 10mm; He needs to be fobbed off and never let him in your house again

 

[monday]

I thought my house built 1997 had microbore heating but I was relieved to be told that it was actually 15mm but the builder (a big national) thought it would look neater to install a reducer just behind the plasterboard and bring the flow and return out to the valves in 10mm. As we chop and change in the 27 years since, these bits of 10mm are gradually being replaced.

 

[Doug99]

I have a 4 bedroom house with microbore CH and Worcester combi.
The only issue I have experienced is a 'boiler engineer' recommended a full system flush last year which then blocked up my boiler.
I now know that flushes should only be conducted on individual rads for microbore systems.
It was a pain at the time, but has now been sorted and the CH now runs efficiently.

My house was built 1990. I have 15mm pipework leaving the boiler but where it reduces to 10mm for the rads I don't know as it is all hidden in the walls.

 

[Johntheo5]

@Tom079555 says his house does not heat properly as is, if its ALL plumbed in microbore then a 6M pump will only circulate ~ 5LPM, only enough to feed say 5 rads at 1kw output each.

 

[polesapart]

Microbore is not garbage. Used correctly it has its place.

It does have a lower heat carrying capacity than a larger pipe and is more likely to block on a sludged system.

My rules using microbore is that each 10mm feed comes off a 22mm flow & return.
15mm is possible depending on how the system has been piped up.

+1

 

[gas112]

Any one telling you that they can tee in to microbore and have another large rad off it is talking absolute nonsense and shouldnt be allowed near a heating system