Replacing a Vokera combi boiler (with 15mm gas inlet!)

[Ces]

Help!

My Vokera 20-80 R.S. Turbo combi boiler is all but dead. Basically it's leaking from Air Release Valve (top of the dhw Heat Exchanger) an the dripping water has caused the Pump over-run thermostat to shor out.

It's an old boiler so now is probably a good time to replace it, BUT:

the gas supply to it is 15mm. I can't find any new boilers with a 15m gas supply pipe, which would mean replacing the supply pipe with 22m all the way back to the meter. I would LOVE to avoid this option!

Anyone know where I might get a re-conditioned Vokera20-80 so I coul do a straight swap, and use the existing one for spares? I tried eBa already.

Alternatively, anyone know of any new combi boilers with 15mm ga inlet?

Failing that, anyone know of a decent plumber in the Brighton&Hove are who might fight to keep my Vokera alive?

Thanks for reading, and thanks in advance for any help you might give.

Ce

-- Ces

[Nick]

Our Wickes combi 101,000 BTU has a 15 mm gas inlet and I reckon the 80,000 BTU one would as well - It is the Halstead Ace High under the Wickes Badge and I thought I saw them in Wickes the other day...

Nick

[John Rumm]

The actual inlet size on many boilers is only 15mm (or 1/2" BSP) - even my 35kW one. The size of pipe you need to feed them with however will depend on the maximum gas rate required by the boiler and the distance from the meter.

You can work this out for yourself with a copy of the boiler install manual and details from the pipe sizing tables here:

[John Stumbles]

If you have a combi with 15mm all the way back to the meter then the pipework is almost certainly undersized already. You are obviously still alive so your present boiler is getting away with it, but it would be illegal to commission any new boiler with such a supply and anyone working on your current might be obliged to issue an 'At Risk' warning notice on it, depending on how low the gas pressure arriving at the boiler is in practice,

It's not the size of the gas inlet (as others have explained some combis have a 15mm inlet but the general rule is 22mm all the way from the meter except for 15mm for the last metre)

Your options are to uprate the gas supply pipe or convert to a stored hot water system which allows you to use a lower-power boiler (providing that a boiler capable of supplying your house's heating load is capable of running satisfactorily off the 15mm pipe). By stored hot water I mean either conventional gravity fed system (yuk), unvented (mains pressure) cylinder (yuk^2) or some form of thermal store (rah!).

If you're in a flat or small house a combi is probably the way to go, but if you're in a bigger house with more demands for hot water a stored hot water system is probably a better investment. (It also gives you electric backup for hot water which a combi doesn't.)

[Ces]

Hello again, and thanks for all the useful replies.

HERE IS AN UPDATE WITH A FINAL QUESTION ON THIS ISSUE

I've got the boiler up and running again (for the £20 of parts a suggested in one reply!) but the drip from the Air Release Valve (dh Heat Exchanger) persists. I'm initially tackling this with LS-X.

I know this'll upset some people, but the part I need to tighten i obsolete and a bit rusty. The consequences of 'breaking' it permanentl are expensive and I'd rather live with the drip for now, rather tha risk it.

I saw the Wickes boiler with the 15mm inlet on Friday. This i apparently old stock, and is being phased out for new 22mm inle variants soon. So it's an option.

But I now also understand a little more about why the gas inlet pip diameter is NOT the only consideration here. And that the pressure i the gas supply can be tested to help me find a suitable replacemen boiler.

Thankfully, on investigation, it turns out the pipe coming into th flat IS 22mm, and disappears into the ceiling approximately 5 metre from the boiler. It re-emerges at 15mm approx. 1 metre from the boiler When I'm ready to start lifting floorboards, and know which boiler might get, I'll investigate further to see how much pipework needs t be replaced.

I will be sticking with a combi bolier since it's a small flat. So m only question now is:

IS IT NOW ILLEGAL TO GET A (NON-CONDENSING) COMBI BOILER FITTED IN TH UK? I ONLY ASK SINCE REGULAR COMBIS ARE STILL AVAILABLE AND FITTING CONDENSING BOILER REQUIRES EXTERNAL PIPEWORK IN A FAIRLY INACCESSIBL AREA.

Thanks again John, John, Raden & Nick. All your help and advice i appreciated

-- Ces

[Ed Sirett]

You may find that there is a small 'dust cap' on the auto air vent which can be closed if the unit is leaking, of course you need top be sure that practically all the air is out first. The auto air vent can also be replaced, it almost certainly screws into wherever it's fitted.

Fitting a non-condensing boiler is invariably illegal now (its against building regs). It's illegal like driving over 70mph. I.e. just because it's illegal doesn't stop it happening quite a bit.

SOME people get UPSET when you use lot of CAPITALS.

HTH