It is currently 29 Mar 2024, 01:34
I've tickled the new PRV to clear any potential gunk... At present the discharge pipe outside isn't dripping.9fingers wrote:In normal use the PRV should just sit there and never operate unless there is an over pressure problem.
I suspect that the new one is operating regularly and hence has got some crud under the valve seat especially if you have been disturbing muck in the system elsewhere.
The question is why is it operating regularly. I would suspect that the expansion chamber diaphragm has failed. This may be integrated into the boiler which makes it bespoke, expensive and a pain to get to BUT it is perfectly permissible to insert a new common one anywhere on the circuit that you can hide a 1 cu ft lump and just leave the defective one where it is.
Fitting one is not difficult and they can be sourced on ebay.
HTH
Bob
Jimmy Mack wrote:...
A sepertate job this week was unblocking a 2m section of 15mm plastic CH pipe as two rads weren't heating at the end of the system...I blame those little inserts at the joints, for reducing the bore.
...
Jimmy Mack wrote:That does help Bob, the expansion vessel (external) is at 1.5bar... Perhaps too high. I've depressed the valve here to drop the pressure... No water discharge, a good sign.
Thanks
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The PRV is rated 3.0 bar. I've dropped the cold pressure right down now... I'm sure I read it was between 1.2-1.5 . This might of been a doctor Google fail.9fingers wrote:Jimmy Mack wrote:That does help Bob, the expansion vessel (external) is at 1.5bar... Perhaps too high. I've depressed the valve here to drop the pressure... No water discharge, a good sign.
Thanks
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Yes indeed a good sign! Why are you setting the cold pressure so high. Manual says 0.7 bar minimum so no more than 1 bar needed surely.
Is the PRV calibrated? I think they are normally set to 3Bar? However being newish we can assume it is OK (?)
Bob
Jimmy Mack wrote:You're right Roger... This is what I said to a British gas chap who suggested all the plastic (Barrier type!) should be removed and replaced with copper, as the plastic causes air ingress and corrosion issues... Etc etc.. He came back with a massive quote. Ironically the Hep2O stuff is endorsed by British Gas!
The blockage was magnate, I believe, it felt like compacted sand when I pushed a coat hanger into it. So I cut it out, cleaned and refitted.
When we first moved in a lot of the rads were isolated, some at both the trv and lock shield return! So indeed the lack of circulation was probably the problem. We have a magna-clean which needs a good clean out every year.
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I got my qualified buddy to check the electrics before we moved in... He noticed the bonding wasn't connected to the main earth!.... The whole house wasn't earthed! He corrected it and also connected the "bypassed' electric shower to the correct RCD which "quelle suprise' subsequently highlighted a problem with the shower appliance... At this point the homeowner actually turffed him out and said he broke the shower... Their conveyancing solicitor sent a snotty letter.RogerS wrote:Ha ha...looking at that last photo looks as if someone didn't understand mains bonding requirements !
Ah!... That's a good bit of sideways thinking Bob...I hadn't considered that external EV was potentially a remedy to a failed int EV, I just assumed it to be that the system was too large for the int alone.9fingers wrote:Most people leave the defective internal EV inside the boiler due to the cost of the new part and the possible complexity of the fitting.
I don't believe that you know why there is an external vessel fitted. It maybe that a previous owner solved the problem in the "normal" way by adding an external EV. That could be undersized now that your system has sprouted extra rads perhaps fitted after the EV was sized.
There are bound to be online estimators for EV size. I would use one of those to see how much margin you have with your current EV and then decide what to do.
hth
Bob
RogerS wrote:Thanks for the heads-up re a potable vessel. Hadn't realised the difference. ST say not a problem, Only drawback is that if the water's not used then the heat is lost..so have to wait longer. But in my scenario, don't think that will be a problem. Food for thought.
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