Non-motoring > Pressurising Boiler Miscellaneous
Thread Author: Bobby Replies: 19

 Pressurising Boiler - Bobby
Down at my MIL's this afternoon and she mentioned she had no hot water - a quick check of the boiler, error code as lacking pressure.

Found the two valves, turned the black plastic knobs and it started to fill up with pressure. All sorted.
But once it got to near 2, tried to turn back off and one of the plastic knobs broken in my hand. Thankfully I managed to grip it tight enough to grip the valve and turn the water supply off.

However made me think, what ultimately happen if I couldnt get this valve turned off? Would the system pressurise until it burst at its weakest point?

What would be the best course of action if valve didnt turn off? I guess try and turn off at stopcock?

 Pressurising Boiler - CGNorwich
Pressure will automatically be released via the Pressure Relief Valve
 Pressurising Boiler - James Loveless
As CGN says, there is no danger, as there is a pressure release valve.

However, if the input of fresh water continues, the inhibitors and other useful chemicals in the circulating water will be diluted and sludge and other nasties will begin to accumulate in the system. (Yes, I had it happen.)

So it's best dealt with soonish.
 Pressurising Boiler - bathtub tom
I'm no plumber, but if it's losing pressure, doesn't that indicate a leak somewhere?

My elderly neighbour has to call out a plumber several times a year to re-pressurise her system. It has to be done from the loft! I know you can get remote pressurising by a bit of plumbing, but she won't listen and I suspect the plumber knows it's an easy call out.
 Pressurising Boiler - Bobby
Every boiler I have known always needs pressurised to a certain degree at some point.

Nothing obvious in this case, sometimes you might see signs of a radiator leak or whatever.
 Pressurising Boiler - Bromptonaut
Still got the old fashioned Baxi installed by the builders last century. Thought about replacing it but as long as it works it seems OK. The guy who services it says that model goes on for ever.

We had one at work, there were several domestic type boilers in different parts of the building, and it needed a top up of water every now and then. Kids have had them in places they've lived too with similar occasional burst needed.

Problem I guess is if it needs topping up every week.
 Pressurising Boiler - zippy
AIUI, it can happen after bleeding the radiators (air pressure).
 Pressurising Boiler - smokie
I replaced my fully-working 30+ yo boiler as part of an update programme 5 or 6 years ago (may even be more) and the gas savings were significant. I can't remember the magnitude now but about 30% saving rings a bell. I suppose that still means it would be quite some time to get your money back but it'd be good for the planet too :-)

Of course the sexy thing to do these days would be replace it wit a heat pump system but they seem to me to cost quite a bit more to install and run (but are even better for the planet).
 Pressurising Boiler - Terry
The loss of water from normal working pressure down to triggering a fault may be 1-3 litres.

If this happens every few months the daily leakage may be in the range 10-30cc a day.

It may not be noticeable - a leak of this size from a joint or gland on a hot pipe will evaporate any water before it marks the décor, drips through the ceiling, etc.

Choice - just top up as and when required - pay the plumber to change the pipework to make it easy not a loft job, or an exhaustive search including the inaccessible which may not give a result anyway.
 Pressurising Boiler - Robin O'Reliant
>>
>>
>> Of course the sexy thing to do these days would be replace it wit a
>> heat pump system but they seem to me to cost quite a bit more to
>> install and run (but are even better for the planet).
>>

We're lucky there. The Welsh government run some sort of scheme where in partnership with the energy companies people over 65 who have a family member with a disability (Mrs O'Reliant) can qualify for a free heat pump and solar panels. Along with about half a dozen others in our cul de sac of crinklies we had ours installed last August, and so far I calculate a saving of over £50 a month on our energy bill, and this will reduce further through the summer as a nice sunny day means we are often getting more back from exporting electricity back to the grid than we are spending on it.

Without the solar panels it would probably be costing a bit more, but the combination of the two works well.
 Pressurising Boiler - smokie
They're pretty generous, these devolved governments!! :-)

Octopus were doing a good deal on heat pumps a bit back and I could have been tempted but some of the conditions would have been hard for me to meet - particularly space for a large tank but not in the loft.

I have a modest amount of panels which cost me £10500 in 2012 and so far I have got back just under £22k tax free, with a further 12 years or so to run. This years rate is almost 80p per unit GENERATED, whether or not I use it. So I also bought a solar diverter to push unused energy into my hot water tank, to maximise my usage. I hardly have any gas usage between about March and October. All in all one of my better investments I think!! :-)

 Pressurising Boiler - Robin O'Reliant
>>
>>
>> I have a modest amount of panels which cost me £10500 in 2012 and so
>> far I have got back just under £22k tax free, with a further 12 years
>> or so to run. This years rate is almost 80p per unit GENERATED, whether or
>> not I use it. So I also bought a solar diverter to push unused energy
>> into my hot water tank, to maximise my usage. I hardly have any gas usage
>> between about March and October. All in all one of my better investments I think!!
>> :-)
>>
>>
>>
That's very good, Smokie.

I'm no plumber but from what I can make out of the heat pump it seems a lot less complicated bit of kit than a boiler, so if they become the norm there is no reason for them to cost any more and possibly even a bit less.
 Pressurising Boiler - Fursty Ferret
>> They're pretty generous, these devolved governments!! :-)
>>
>> Octopus were doing a good deal on heat pumps a bit back and I could
>> have been tempted but some of the conditions would have been hard for me to
>> meet - particularly space for a large tank but not in the loft.
>>

I have an Octopus heat pump. Cost me £3,000 with the grant and included the unit, new water tank (and relocation from airing cupboard to garage), and three radiators. So far it's costing me 2p/kWh to run. Haven't done a winter with it yet though...
 Pressurising Boiler - zippy
>> So far it's costing me 2p/kWh to run.
>>

Is that on a special tariff?
 Pressurising Boiler - Fursty Ferret
>> >> So far it's costing me 2p/kWh to run.
>> >>
>>
>> Is that on a special tariff?
>>

Intelligent Octopus Go at 7p/kWh. It’s running at 400% efficiency with the warm weather so just sipping at electricity for hot water.
 Pressurising Boiler - Dog
>>I have an Octopus heat pump

Have you considered getting battery storage - charge it up at night on them there the cheap rates.
 Pressurising Boiler - Fursty Ferret
>> >>I have an Octopus heat pump
>>
>> Have you considered getting battery storage - charge it up at night on them there
>> the cheap rates.
>>

Yep, 10kWh. They charge on the 7p/kWh overnight rate or whenever the car is charging during the day if Octopus schedule additional slots.
 Pressurising Boiler - Dog
>>Yep, 10kWh.

Proper job!
 Pressurising Boiler - smokie
I understand the battery decision is quite complex, even if you take is as a given that there will always be a cheap tariff. Having said that I know there are people earning a reasonable lump from exporting power from the panels and batteries. (They often forget that their tech has cost £10k upwards though, and the batteries have a finite - albeit reasonably long - life :-) )
 Pressurising Boiler - Dave_
>> what ultimately happen if I couldnt get this valve turned off?

Your mains water pressure will be no more than 10 bar, and probably substantially less. All the pipe joints on your heating *should* be able to handle the equivalent of mains pressure, as they're the same type of joints as the ones leading to your taps etc. The boiler would have a pressure release valve though, as others have said. To then reduce the system pressure without disconnecting the filling loop you'd just open the drain cock at the lowest part of the system; although the concentration of inhibitor would indeed be reduced.
Last edited by: Dave_ on Sat 7 Jun 25 at 18:30
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