safe to turn off my old boiler for 3 weeks?

pigeonpie

In our flat we have a cupboard based Powermax 155x combi boiler (big thing: takes up the whole cupboard, has a small hot water storage tank bit and round pressure valve on the wall), about 10 years old.
Last time we went away in (cold) January for 2 weeks, we left it on low - on for 1 hour 2x daily - and when we came back, the pressure needle had gone to nearly 3. It's supposed to stop at 2 at the most and in general usage it stays at 1 1/2. We had to run a lot of hot water to get it to go down and a B Gas Home care engineer had to come out as that took a few days to sort out.

We are going for 3 weeks this summer. We are thinking of turning it off (assuming can work out how to do that!). The heating's obviously off but the hot water is on all day. Just wondered if it was safe to do that, or a good idea - don't want either to flood my flat or my downstairs' neighbour or to come home and the boiler doesn't relight as it's not ever been turned off in those 10 years.

Then again, if we leave it on, it'll be an extra week from last time without any hot water being run and the pressure may go up to 3 or more. I don't know why it did that and if it was because the winter was so cold. It's a cranky old thing but we can't afford to replace it and don't want to do anything that invalidates our B Gas home care. They don't seem to have an advice line for general boiler queries and I don't know any friendly plumbers.

thanks if anyone who knows this boiler (common lousy boiler in flats according to B Gas home care engineers) has any answers for us. cheers.

Owain_Moneysaver

pigeonpie wrote: »

In our flat we have a cupboard based Powermax 155x combi boiler (big thing: takes up the whole cupboard, has a small hot water storage tank bit and round pressure valve on the wall), about 10 years old.

Strictly speaking this is not a combi boiler, which heats water on demand, but a boiler and thermal store combined into one unit, where the thermal store doubles as the boiler heat exchanger. Incidentally, the Powermax have some 'peculiarities' which make servicing both difficult and expensive, and can be safety related. Note the comments on concealed flue here.

Normal advice would be:

The boiler radiator circuit should only be connected to the mains water when refilling/repressurising is required by a boiler filling loop.

This should be disconnected and removed when not required. If yours is permanently connected it's possible that the valve is letting through and the system is slowing approaching mains water pressure, which may be as high as 10 bar.

However I don't know what the arrangements for pressurising radiator circuit is in a Powermax.

Owain_Moneysaver

BTW, if you just need to depressurise the radiator circuit you can do that simply by bleeding a radiator. Be prepared for mucky black water to squirt out - it stains carpets indelibly. A more sensible installer will have provided a drain tap somewhere you can attach an 'ose .