Microbore or 15mm pipes & which boiler? *Now with added queries!*

jamtart6

sorry EliteHeat.

We have a naff old Baxi Boiler with a glow worm switch and a flue out the back of the house.

The heating system is on 10mm pipes.

There is a monstrous water tank in the only cupboard in our upstairs.

We want a combi so that we can get rid of the water tank. We want 15mm pipes (maybe) because our Dad's have said they are much better(?) and we need to move the boiler and get rid of the flue as we are having an extension. The rads get luke warm and nothing more.

That is the state of my knowledge of our heating system!

EliteHeat

If your radiators are getting even slightly warm then you have circulation, this can be improved by power-flushing which you would probably want on a boiler swap, even if doing some re-piping. 10mm is easily OK to heat individual radiators and if you’re still not happy then you should think about 15mm.

15mm copper pipe can carry about 5kW of heat, but this is often shared across two or more radiators. 10mm will obviously carry less, but each leg is only servicing one radiator, so you really shouldn’t need to spend the extra £££s, unless of course your multiple dads are footing the bill.

jamtart6

multiple dads are not footing the bill - they are trying to be helpful where we know nothing!

Plumber #4 (or is that 5?) said he didnt think we needed new pipes either, as its likely that the main pipes will be much larger and only the 10mm ones that go up to the 'rads' (I'm down with the plumber lingo now).

So...hopefully we've decided now! Just deciding which of the plumbers to go with now is the problem! I'll keep you posted as it is helpful for others in a 'heating system dilemma'

EliteHeat

jamtart6 wrote: »

I'm down with the plumber lingo now

Good for you. Don't let them fob you off with ungalvanised flange sprockets though. I couldn't begin to describe the consequences of that one.

jamtart6

I certainly won't! Those ungalvanised flange sprockets are the worst!

roddydogs

Dosent the feed from the boiler have to be 22mm..then to 15mm for the rads?

EliteHeat

It is, it goes to a manifold.

jamtart6

Still haven't decided what to do with the microbore issue! We have now definitely decided where to put the boiler.

Decisions still to make :

* Which boiler to get ? (everyone says Worcester)

*Which size pipe? Stick with 10mm or get it changed to 15mm?

*Think the main pipes are 22mm so can we just get the 10mm changed to 15mm up to the radiators?

* Should we just get a whole new system even if they are 22mm under the floorboard so that the whole system is brand new? (this feels like a waste of money)

* Copper pipe vs. plastic pipe - which is best??

Answers on a postcard MSE Plumbers...!

jamtart6

Hello! Is anyone out there??

We got the floorboards up tonight. It appears the pipes are 22mm off the boiler (will they be using the same pipes if we replace the Baxi with a combi?)

then they go to 15mm and then as they arrive before the radiators they turn into 10mm, so not much of the pipes need to be replaced.

Obviously the house is 25yrs old - would it be best to get the system replaced now anyway? I know there are no guarantees old/new but I would appreciate further advice.

Thinking of just getting the small amount of 10mm replaced with 15mm rather than a brand new system....

latecomer

sounds like you have bigger issues that just the microbore. We've got a Baxi bermuda back boiler which is approx 20 years old (we think it hasn't been changed since the house was last sold). We have 22mm pipe from the boiler which runs down the middle of the house and from there splits off into 8mm microbore. I moved and upsized a radiator in our bedroom so its now got approx 15' of microbore to the radiator and it gets the radiator hot despite it being a triple 3kW monster.

I fully intend to replace all the 8mm pipe with 15mm when we have our boiler replaced as I bought a load of 15mm copper a while back.