Boiler overpressure with Potterton Precision

[sutty600]

What had 'zero change'? Has removing the link stopped the pressure buildup in the heating system or not? (I suspect not but I try to avoid assumptions.)


Can you post a photo of the tank and nearby pipework? (Just want to check we really do have an unvented cylinder.) Also, what make and model of boiler do you have?

The inlet to the cylinder will be at the bottom. So will be the flow and return to the heat exchanger. There is usually an expansion vessel, maybe 20 litres in volume and painted white between the isolation valve and the cylinder.

Nice one, thanks. I meant zero change in the dry status of the now opened ends, after having dried them with tissue, and having waited several minutes. with the link completely removed, waiting for drips, from either side, but both ends remained bone dry. Thanks for checking.

There is a white expansion vessel. It's roughly the same height as the red expansion vessel. I only had a quick look for the valve, but will try harder tomorrow. If I get a moment to nip up tonight, I'll take some shots, but maybe the white expansion vessel is a giveaway for you?

 

[sutty600]

As per the title, it is a Potterton Precision boiler, though if you need more, let me know. Sadly I haven't had the time to do anything today, due to family commitments, apart from to bleed it, to make it work. I've also just turned off the hot water, on the controller, so see if that would stop the tank crossover, if that's where it is occurring. I figured, if the heating system isn't putting hot water through the tank, maybe it's less likely to be able to be back filled by the heating system? Dunno, but I'm trying it.

I'll be without hot water in the morning, but I can soon correct that, by putting it on for an hour.

Doing so got me to wondering if there might be other potential crossover points, especially with you telling me that there would not be another fill point, and it got me to thinking about what our hot water does. Maybe this will help you to help me, or not, I'm not sure?

Unusually, judging by every technician/plumber that has ever visited, or any friend that I have mentioned this to, when our hot water is on, whether the central heating is on or not, three of our radiators get hot. They get hot, deliberately so, at the request of my late mother, who always wanted to have the bathroom radiators on with which to dry things, if she needed to. It also afforded us the luxury of being able to heat the bathrooms, even if the CH was off, so they were a little warmer, when having a bath, etc, on an averagely warm day, by simply putting the hot water on.

If not needed, in say the height of summer, when it would simply be wasting money, but we would still need hot water, they were simply turned off with the radiator valves.

So, we have three radiators that come on whether it be hot water or central heating that is on, with the only difference being that if they come on as a result of CH, then they are on with all the others. I have no idea how that works, but for sure, it does exactly that.

Maybe this isn't so odd, but the reactions I get seem to suggest it is, but does this suggest there might be some other potential crossover point, or not?

Thanks again for any help.

 

[sutty600]

No pressure increase, in the absence of hot water being on. To me that points to what you said, in terms of pressurised tank water crossing over into the CH circuit, although I still have concerns that I'm not at the bottom of it, what with the system's own peculiarities, of having those three radiators that come on with either the HW, or CH. Of course, I don't understand, so this could be a complete red herring.

I have taken photos, see attached, which may help work out what's going on? This system has been in place for as long as I can remember. Certainly long before my father passed, which was 16 year ago now. Probably some 20 years, probably more, I should think, apart from the boiler, which is just 11 years old.

Flexible link (foreground right) and tank overview.

Link in other direction, to red vessel, with pressure gauge on top.

Under white vessel. Some sort of capped controls?

Some sort of vent or overflow mechanism, to the right hand side of the picture? Have never observed anything running down it, and it's bone dry right now.

Thanks, if you can offer any further help.

Cheers

Sutty

 

[Chuck]

No pressure increase, in the absence of hot water being on. To me that points to what you said, in terms of pressurised tank water crossing over into the CH circuit, although I still have concerns that I'm not at the bottom of it, what with the system's own peculiarities, of having those three radiators that come on with either the HW, or CH. Of course, I don't understand, so this could be a complete red herring.

If the pressure rise in the CH stops when you reduce the pressure in the hot water cylinder that tells you that the heat exchanger coil in the cylinder has failed, which usually means that the cylinder will need to be replaced. This is a job that can only be done by a plumber with an 'unvented hot water' qualification, sometimes called a 'G3 ticket'.

Bathroom radiators (particularly towel rails) are often plumbed to be 'always on'. It's unusual to have other radiators configured in this manner but it should be fairly straightforward to have them put onto a controlled zone.

Unvented cylinders usually have a long warranty (25 years+) covering the coil and cylinder. There should be a label showing the maker, model, serial number and date of installation on the tank so you can contact the manufacturer to see what the position is. They probably won't pay for the labour but you may get a free / reduced price cylinder.

You have a lot of underinsulated pipework in what looks like a 'cold' roof space. This means that there is a risk of freezing during the winter if the heating can't be left on. I'd want to have a 'frost stat' up there so the heating turns on You're going to have to get a Homecare or a G3 qualified plumber involved.

An unoccupied house with a faulty heating system needs to have the water shut off at the stopcock and then be fully drained, preferably by a qualified plumber.

I don't know how Homecare handle the death of a customer. Standard practice is for the executor(s) to contact the company and arrange to continue making monthly payments to continue the deceased's cover until probate is obtained and the house, and responsibility for its maintenance, passes to the beneficiaries. Big companies usually have a 'bereavement department' who understand the situation and do their best to help.

 

[sutty600]

Thank you for the detailed and considered response. Yes, it would seem that I have no choice now, because that would be far beyond me. Interesting to know that it may be under guarantee. I saw the manufacturers label on the tank, and will see if it is.

As for Homecare, one might hope that they would have a department such as that, expert in such matters, however it would seem not. After having made contact, advising them of the required changes, as a result of the death of Mrs Sutty, I received an email back, saying, thank you very much for notifying us of the changes to your account, Mrs Sutty. I promise you I could not have made it clearer that she had passed away.

Eon, on the other hand, as the energy supplier, were simply fantastic, and dealt with everything in an incredibly professional and sympathetic manner.

I will try to call out Homecare in a few days.

Thanks for your help in properly identifying the issue.