Woke to a wet patch under a TRV - potential cause and possible fix?

Bendy_House

Fair do's, Boo. That's why you are paying for their service.

Keep us posted, please

BooJewels

When I got up this morning, it was all quite wet again and didn't clear up once it got warm - it carried on oozing from then on, so seemingly a modest deterioration.  A chap from Dyno Rod came this morning and has changed the TRV and as it was upstairs, he only needed to drain part of the system, so it was all done and dusted in about 40 minutes. 

I've had a bit of a task since getting the air out and pressure back up and the radiators balanced again (he offered to do that, but I know how I like it and what works here) - but it seems settled now.  He rather pessimistically suggested that the rest will probably go soon, as 6 were installed together.   He looked on his tablet at my request and said the magnetic filter had been checked in the last service in November.

I'm not entirely sure that the pressure system/display is working quite right on the boiler, as previously touched on - so I'll keep my eye on it.  It went from displaying 1.7 bar to a low pressure fault and turning the heating off in a few minutes.

I'm hoping that's the drama done with.  I haven't put the towel in the wash yet though!

FreeBear

BooJewels said: He rather pessimistically suggested that the rest will probably go soon, as 6 were installed together.

If they are all of the same brand & age, it is not an unreasonable conclusion that the rest may fail in the same way before too long. It might be a few months, or it could be years down the line - Do you know how old the TRVs are ?

BooJewels

Clearly a sensible deduction @FreeBear - I was just hoping that it could be attributed to a one off catastrophic failure - not just old age. They are all the same age, installed at the same time. 

I think they were changed at the same time we had the last boiler installed which was December 2000.

We did discuss changing them all, but that would be classed as an upgrade and not covered by the warranty terms applicable today.  Had I just hired someone to do the job today, we could have negotiated a price for doing them all at the same time. 

Bendy_House

BooJewels said:

When I got up this morning, it was all quite wet again and didn't clear up once it got warm - it carried on oozing from then on, so seemingly a modest deterioration.  A chap from Dyno Rod came this morning and has changed the TRV and as it was upstairs, he only needed to drain part of the system, so it was all done and dusted in about 40 minutes. 

I've had a bit of a task since getting the air out and pressure back up and the radiators balanced again (he offered to do that, but I know how I like it and what works here) - but it seems settled now.  He rather pessimistically suggested that the rest will probably go soon, as 6 were installed together.   He looked on his tablet at my request and said the magnetic filter had been checked in the last service in November.

I'm not entirely sure that the pressure system/display is working quite right on the boiler, as previously touched on - so I'll keep my eye on it.  It went from displaying 1.7 bar to a low pressure fault and turning the heating off in a few minutes.

I'm hoping that's the drama done with.  I haven't put the towel in the wash yet though!

Yes, it's an annoying situation, where you cannot have them replaced under this contract until they actually leak :-) Tbh, I think they are more likely to simply stop working, rather than leak. Usually the 'head' fails, so it doesn't control the rad properly. Or else the valve sticks closed, or the pin doesn't move.

Anyhoo, don't worry about it. When another one fails - and it could be a long time from now - then, yes, get them all done as a lot. You never know, you might be ready for 'Smart' valves by then :-)

If there was air in your system after this job - and it sounds as tho' there was - then it wouldn't be unusual for the pressure to drop from 1.7 to zero after the rads were bled. From your description from page 1, it does sound as tho' your system has a tendency to trap any air in there, and make it difficult for it to be bled out. However, it also appears as tho' you do ultimately get there!

A rad with air in it will usually show itself by having a cool top. A lot of air can even make most of the rad stop working, so only the bottom will become warm. So, if you get your system to the point that every single rad becomes nicely hot when you've finished bleeding them, then you should be good to go from then on - you should not have more air appearing (apart from very small amounts that shouldn't affect a rad), and - if you do - then there is likely something amiss (ie, air is surprisingly getting in).

Also, once bled and stable, your system pressure should also settle at around one place, and only vary a small amount - say 0.2ish bar - between hot and cold (tho' some are ok doing more than this.)

You mention 'balancing' your rads. 'Balancing' your rads actually means setting them up so that each rad receives the correct amount of hot water flow, regardless of how large they are, or how close or far from the boiler they are. It typically involves opening up their 'control' valves (eg the TRV) to 'max', and then tweaking the other valve - the 'lockshield' - to the point each rad is getting the right amount of flow. The rads closest to the boiler will usually need to have their lockshields turned down further. Once this has been done for all the rads, then the 'control' valve is adjusted to provide that room with the desired temp.

Is that what you have been doing? Ie, tweaking the lockshields? If not, what else?

BooJewels

Many thanks again for your patience in explaining @Bendy_House - I think maybe sometimes I don't use the right terminology.

I'm actually surprised that the chap on Friday did check the TRV (I didn't see him do it, but he said that he had), as looking at the pin area - even to an untrained eye - it looks corroded and the pin feels stuck - I've unstuck one before, so knew what it would look like inside.  He asked me today what exactly the other chap had done (he used his name, so he knew who had been before) and I wonder if he drew the same conclusion that I did.

I'll monitor them and if another looks like it might be going, maybe organise it as a 'replace them all' arrangement and pay for that.  Smart valves!  I must admit, being new to Hive, which I wasn't even sure I wanted, I have quickly got used to being able to look at it and make adjustments on my phone.  When I stayed at my parents' house that I've been clearing recently, I was able to put the heating on here with a low temp, just to keep the house chill-off whilst away, then turned it back to the usual schedule from 50 miles away as I set off home and it was toasty warm when I came in.  That's just crazy bonkers!  The other night when I got up to check the valve in the wee hours, I opened the app to put it back to scheduled heating and went back to bed and was tickled to see that the temp was 17.6 at 05:00am which seemed very warm to me overnight, clearly a very mild one.

There hasn't been any air in the system since the new boiler was installed, just this incident on Friday, then getting it straightened out after today.  It has been settled with no noises and no air at all from the bleed valves, the couple of times I quickly checked.  The system always was prone to air - it was a perpetual issue with the last non-combi boiler.  Hopefully it's now settled for a bit.  He did say that this boiler has a purge valve or something for air and tends to keep on top of small amounts.

When I got a lot of air out of the big kitchen rad this afternoon, it was cool at one end and warm at the other, which is less usual - but a lot of air came out of that.  The rads are all now where I like them, all evenly warm across their size and some rooms a bit warmer, others cooler.

Sorry, maybe by saying balancing, I was using the wrong term.  They were balanced, as you described, when the previous boiler was installed by a lovely engineer who got to know our old system well (in the days when nearly the same engineer came to each service or repair) and worked on it with me over quite a while to get it right.  I now tweak the TRVs to get each one how I want it.  But it's a subtle tweaking - where engineers tend to just open them all up and say "yep, it's hot".  All of mine are set at around 2-3, but one has to be on the front side of the 2, another has to be at the start of the arrow going towards 3, etc etc. I have a diagram of how I know they'll be just right - then I just leave them alone.  Once they're right, I don't touch them.  Then an engineer will come to a service and start messing with them, hence I have a note of how to set them.  

Bendy_House

Sounds like you have it all in hand :-)

And I hope you are no longer troubled by air - barp.

BooJewels

Thank you kindly - I hope I'm not troubled by oozing water again either!   

BooJewels

Me again, sorry.  I have another similar issue.

A couple of evenings ago, on one of the warm days, I had noticed during the day that the heating had been firing up for very short periods and I figured - without too much actual conscious thought - that it must be very close to the thermostat temp and it only needed to fire for a few minutes.  Late in the evening, I decided that I was now feeling a bit cool and the heating hadn't been on for a while, so I checked everything.  The thermostat showed something like 17.9C actual temp with a target temp of 19C, the heating being on, but it wasn't.  So checked the boiler.

The boiler appeared to be on - i.e. green light lit, but wasn't actually firing.  There was an F22 error and a pressure of only 0.1 bar.  I filled the water up to about 1.7bar (annoyingly the pressure display always seems to time out/switch off when you're getting close to target) and let the boiler do its thing re-booting.  Boiler fired up properly after a few minutes, everything fine since.  I checked the base of all the TRVs to see if I had another leak and all were fine.

Then this morning, I remembered this - I noticed a few weeks ago an occasional small damp patch on the cellar floor underneath this little tap jobby in the pipes - this is looking up to it in the cellar ceiling - it must be one of the pipes that supplies the radiator in the lounge above - or maybe after that rad, is en route to the bedroom rad on the floor above that.  The pipe is hot, so it's definitely a heating pipe.  Every time I've spotted the wet patch, I've felt the tap and it's never been wet at all - so I didn't know if it was condensation forming and dripping, or it leaks when cold overnight.

The damp patch is a bit more substantial this morning, as below.  Although I did go down into the cellar this morning much earlier than I usually do, so it would be suggestive of it happening overnight when cold, as there is a timed heater nearby and a dehumidifier in there too - so I would expect it to dry out during the course of the day, when the pipe will be warm and the heater has done its hour in a morning.

Is this the likely culprit for my lost pressure - and can it be tightened up - presumably that's what the square key bit is for?

Bendy_House

Yes, and yes.

Very likely the culprit, and a gentle tightening - a 30th of a turn (unless it feels loose, in which case tighten it more like you would a normal tap) should sort it. A rad key might fit?

That's a drain-!!!!!!, used to empty your system for maintenance - you put a hose over the spigot, and undo the nut a few turns. (Not fully or it'll pop out!)

It has a rubber sealing washer inside like traditional taps.