Central heating system leakage - need advice please

[LikeMyHome]

That's technically enough for 10 rads but you'll need to replace it regularly to keep the levels correct. A test kit would be useful - this one will do 25 tests. Just close one radiator, drain about a litre out then squirt the inhibitor in

I assume the test kit is to compare alkalinity between mains water and that in CH system. Is it to be done only before/after injecting inhibitor or in-between the injections too? How often?

 

[LikeMyHome]

Tie a plastic bag over the end of the Pressure relief discharge outside, and leave for 24 hrs. See if this collects any water, to rule out the simpler things first.

I've just checked - when the boiler is working, a wet hot steam comes out constantly from the pressure relief pipe outside at a rate that my hand gets wet in 5-10 sec. At such a vapor flow is it safe for the boiler to put a plastic bag around the relief pipe when the boiler is working??

 

[Nozzle]

Tie a plastic bag over the end of the Pressure relief discharge outside, and leave for 24 hrs. See if this collects any water, to rule out the simpler things first.

I've just checked - when the boiler is working, a wet hot steam comes out constantly from the pressure relief pipe outside at a rate that my hand gets wet in 5-10 sec. At such a vapor flow is it safe for the boiler to put a plastic bag around the relief pipe when the boiler is working??

You don't need to try the bag thing - the evidence of the relief valve passing is plain enough to see. Though you need to be sure that relief valve is on the primary circuit that the filling loop is attached to, and not just the relief for the cylinder.

 

[dilalio]

You could be in luck here... If the Prv is letting by then replacing that may just be the solution to your problem... Fingers crossed.

 

[LikeMyHome]

Though you need to be sure that relief valve is on the primary circuit that the filling loop is attached to, and not just the relief for the cylinder.

How do I check this?? What is primary circuit? filling loop? cylinder? This is Chinese to me, please explain.

 

[Nozzle]

Though you need to be sure that relief valve is on the primary circuit that the filling loop is attached to, and not just the relief for the cylinder.

How do I check this?? What is primary circuit? filling loop? cylinder? This is Chinese to me, please explain.

Follow the pipe with the steam coming out back to the relief valve and then take a photo of the wider area showing how it is plumbed into the cyilinder, or near the filling loop, or wherever it is installed. Do you know if you have a vented or unvented system? (you may have stated earlier, but I've not read the whole thread)

Nozzle

 

[LikeMyHome]

I think I figured it out - there are two pipes coming outside - wide plastic one (~ 3 inch in diameter) and narrow copper pipe (~1/2 in) bent towards the wall. So I guess the wide plastic is what you called "relief for the cylinder" and the narrow copper one is relief for the filling loop. Correct?
In my post #17 I I was referring to the wrong pipe (the wide plastic).

But a good news (hopefully) is that the copper pipe is also leaking - I've just a plastic bag around it and it drips, slowly but drips - like a teaspoon in 2-3 mins.
I left the bag on and will keep checking on it - will post the update shortly.

 

[muggles]

The wide plastic one is almost certainly the condensate drain from your boiler, and should be plumbed into foul drainage. It certainly shouldn't be open to the air, or running onto open ground

 

[Gas2Air]

The wide plastic one is almost certainly the condensate drain from your boiler, and should be plumbed into foul drainage. It certainly shouldn't be open to the air, or running onto open ground

I reckon this 3 inch plastic pipe he's referring to is the flue. I also reckon the PRV may now be passing as was stated earlier when engineer filled it to 3 bar and didn't drain after to correct pressure. Plus any engineer would know how to test for a passing PRV.

 

[dilalio]

Op: please attach some photos coz we seem to be talking very different languages

 

[LikeMyHome]

I've remembered - the wide plastic pipe is the flue. Is condensate drain and flue the same thing? It is not plumbed anywhere, just open to air.
The bent copper pipe (like a hook - coming out of and facing the outside wall) must be the relief pipe. There is ~ 100ml of water in the bag attached to the copper pipe after ~2.5 hours. Left the bag overnight to measure the leak more precisely.

Photos are coming very shortly.

 

[LikeMyHome]

Here are the pictures:
1. Boiler - white pipe at the top connects through the wall to the wide plastic pipe (flue) outside.
2. The flue - front view from outside. Light seen at the center is the light passing through the white pipe from image 1 and the hole in the wall.
3. The relief copper pipe with a plastic bag around it.
4. Water in the bag from image 3 gathered after ~2.5 hours. Bag size is 240x340 mm^2 (=9.5x13.5 in^2)

 

[Agile]

Its a bit too basic for me!

 

[dilalio]

It's only simple when you understand, Tony .

OP: the bent copper pipe is your discharge from the boiler, it is connected to the pressurised central heating circuit and is governed by a PRV (pressure relief valve) which is a safety device that allows expanding water to escape if the pressure gets to high due to overfilling/overheating. If the PRV is defective, it can allow the escape of system water at a much lower pressure level than it is rated to, hence the drop on your gauge and need to frequently top up.
As you have collected water in the bag you tied around it, it would appear that it is defective and is letting by! Get this looked at and possibly replaced but do not rule out other leaks on the system.
Call an RGI and suggest to them that you "suspect" the PRV is letting by and could they please come and have a look for you...

 

[LikeMyHome]

Quick update.

Water leakage through the PR pipe is ~0.2 liters/24 hours .
To refill boiler pressure from 0.8 to 1.5 bar takes 10 sec, and on my estimate takes less than 1l of water, so 0.2l/day is not negligible and hence PRV valve must be faulty.

The plan of action:
1. Find GRI and get an estimate for PRV replacement.
2. Refill the central heating system with inhibitor.

Does it sound OK?