Baxi Solo 80 - pressure dropping every day

bunglemark2

Hi all

I have a couple of problems with my central heating system and am hoping someone can shed some light.

1. One of the rads ("outside" in a sunroom) doesn't heat at all, normally. The exception is when I close all the other rads in the house, force water through this one alone, and very slowly it heats up to running temperature. Then, when I turn on the rest of them it's fine for a day or so. After that it's back to its cold state...
2. In order to force the water into the problem rad, I upped the pressure in the system to ca. 2 bar. I had to basically, 'cos every day the pressure drops to near 0, or just above it. I'm finding I have to top up - via the valve on the cold feed pipe in the hot press - almost daily,.....and I don't think that's right.

The boiler has been serviced recently so I'm not worried about that.

I can't see any evidence of any leaks from the rads anywhere in the house and I've checked them all for even the smallest drop.

I'm wondering if the expansion (red) tank in the attic needs somehow to be re-pressurised ? Or failing that, do I need to drain the whole system and refill ? I also noticed I don't have one of those handy little valves for draining on any of the rads in the house, so presumably one of them will have to come off, hose attached and drained that way ?

Please - all suggestions welcome...

Ta!

Seamus Farrell

Bunglemark2,
You posted a question on the thread I started here. Even though my heating system is not pressurised as yours is, nevertheless my experience might prompt a few questions.
1. Is the water you are having to replace via top up ending up in your cold-water tank as it was in my case. My leak was more than enough to fill the tank to the overflow pipe and then fill a bucket overnight. If the leak is small, then you may have to measure the tank level very precisely with a few hours in between, while nothing is being drained from the tank.
I had the luxury of being able to cut off the connection between cold-water tank and the hot-water cylinder, the route that the leaked water was taking up to the attic, and that stopped the overflow and stopped the central heating reservoir tank filling.
2. Is the hot water in the taps dirty, suggesting contamination from the central heating system.
3. Is the cold water coming from the tank to your taps warm at all, also suggesting the same contamination.
If the answer to these is yes, then it seems to me that it has to be the coil. It's the only place that the heating system and the hot water system are in proximity.
A plumber I spoke to since told me that the problem is uncommon but not at all unheard of.

My new cylinder (factory insulated) cost €150 inc vat.
I expect a professional plumber would have got the whole job done in three or four hours, not including diagnosis and getting required parts.
I did it myself - the other thread includes a post giving some details.

bunglemark2

@Seamus
Not sure I understand all of your questions, but as far as I can make out, the top-up valve is letting mains cold water into the heating system (circuit) - the pressure rises when I do this, so that's the assumption I'm making via-a-vis where it's going !!
The water in the hot taps is clear - I'm not sure if it *has* to be dirty if it is the case that there's a leak from the coil into the hot tank itself.
As for the cold taps, I thought they were all mains fed - upstairs included - so why would these be warm ? Haven't actually checked so I'll do that.

Incidentally, when I spoke to a plumber I've been using over the years, he's quoting ca. €400 to replace the tank. When I read below that the tank itself costs ca. €150, it makes me question his quote.....

Seamus Farrell

Bunglemark2, here's where my experience probably runs out. However...
Let's assume that there is a leak in the coil:
- While discolouration in the hot water coming from your taps would be a good indication of the leak, I expect it would depend on both the size of the leak, and on the colour of the water circulating in your heating system. So, the absence of discolouration doesn't necessarily negate the leak.
- With repect to whether the cold water in the taps is 'warm', and your impression that cold taps are all mains fed. My impression, contrary to yours, is that plumbing regulations in Ireland mandate that the only tap in a domestic plumbing system that may be fed directly from the mains supply is the kitchen cold tap. All other water in the house must be supplied from a tank, typically in the attic (being the highest point on the house) and piped from there to the hot water cylinder and to cold water taps in bathrooms and toilets. In my set-up there is a separate small mains-fed tank in the attic providing a reservoir for the heating system, and as described in the other post (here), the water leaking from the heating system into the hot water cylinder was at higher pressure (in my case because the heating reservoir tank was higher than the main cold-water tank in the attic, and perhaps in your case bacause your heating system is pressurised), and so was pushing hot water from the cylinder up into the main cold-water tank in the attic. That warmed the cold water in the attic tank and so the cold taps ran warm. However, as for the discolouration of the hot water in the taps, that would also depend on the size of the leak, which as I've mentioned was enough to overflow the main cold-water tank in the attic and fill a bucket in an hour or so. The extra water you are having to top up must be going somewhere, and if it's leaking from the coil, and all of your hot taps are turned off, the only place it can go is up into the cold-water tank. If, having topped up the heating system, it was feasible for you to somehow measure the level in that tank during a period when there was no water being drawn from it (i.e. overnight, and ban any use of water for the period except from the kicthen cold tap), you should see the level rise by whatever amount had leaked through the coil, and the sme amount you have to top up by to restore pressure. If the leak is small though it's not going to be too easy to spot the rise in level.
IN any event, you've talked to your plumber, and since he's quoted you, then presumably he thinks the leak is the cause of the pressure drop. With regard to the price he's quoted you, I can't see the job taking less than 3 or 4 hours even for an experienced plumber, and presumably he has to go off and get the new cylinder and so on, so €250 for his labour doesn't sound that excessive to me . . .

bunglemark2

Hi again
1. On the discolouration, I agree. Not a good enough acid test.
2. On the feed for the cold taps, again, of course you're right - I must've been having a blonde moment

As far as an update goes, I had the plumber here again today. Basically he isolated the flow and return into the coil in the cylinder, effectively stopping anything going into it, drained it, and waited 10 mins or so to see if any water from the cylinder leaked INTO the coil...which would suggest a leak in the copper coil.....but nothing came out the bottom of the coil......so I guess we're still no further along. Possibly the next thing is to pressurise the coil and see if there's a leak under a bit more pressure.
All I know at this stage is, after having the system drained today, then refilled back to 2 bar, I went out for a couple of hours this evening and when I came back it was at Zero again. And even more amazingly, I opened the valve to let more water into the system to try to turn the heating on this evening, and withing 5 mins or less, the gauge was down to zero.
There are no feckin' leaks in the rads; I have a bag on the overflow pipe outside (the release pipe from the boiler) and it's bone dry - no water coming out...
If there is anybody reading this - any ideas ? I'M baffled; the plumber's baffled....It's doing my head in and the kids are cold

gorwanvfr

Might be a complete long shot but could the heating coil/jacket within the boiler have a crack in it. When the boiler is running the heat expands the crack the water leaks out. The heat with in the boiler vaporises the water and it goes out the flue as steam? I know it a far out idea but if you can’t find anything else might be worth checking.

bunglemark2

At this stage I reckon it has to be a problem in the tank with the coil. As I say there's no water anywhere in the house - touch wood ! - from leaking radiators. I've let that much water into the system over the past weeks that I should be in Noah's Ark at this stage !
I'm getting a second opinion - have a bloke coming this afternoon. The kids are frozen, poor crayturs, and I'm fed up with the whole fiasco..
Will keep you posted.
Any other thoughts appreciated.

bunglemark2

Update on this folks...

Turns out it was a leak after all. In brief, I have a sunroom which was built after the main house was built (before I bought the house). Rad in the sunroom was plumbed direct from the hot press, over through the attic, fished down the wall, between the plasterboard and out. It's possible that the pipework wasn't lagged and developed a leak, 'cos the plaster on the wall where the rad is is damp/soaked. I can hear the water leaking into the plaster....and am hoping it isn't bad enough to screw up the wooden floor out there !
So, the rad is now blanked off completely, no heat at all in the sunroom. I'm gonna get a bloke to splice off from the kitchen rad and put a new one the other side of the wall (in the sunroom) instead.
Luckily I got a second opinion, 'cos I would have ended up with a new cylinder for no reason, and STILL had a leak....
Still a pain in the hoop though....

bunglemark2

Quick question folks...
Any ideas what it *should* cost to supply and fit a new rad (say, 1600 mm, the one with the grille on top) i.e. to splice/connect to an existing rad on the other side of a wall ?
I have a quote but it seems a little on the high side for what's involved...
Cheers

bunglemark2

bunglemark2 wrote: »

Quick question folks...
Any ideas what it *should* cost to supply and fit a new rad (say, 1600 mm, the one with the grille on top) i.e. to splice/connect to an existing rad on the other side of a wall ?
I have a quote but it seems a little on the high side for what's involved...
Cheers

Any takers on a quote, folks ? Job is still up for grabs...
PM me if you feel like replying...