Finding A CH Leak

Hello Forum!

I hope you're all well and good in this New Year so far.

I think I have a leak and I would like some help from you all building a diagnostic pathway; with, I presume, "No leak and a misunderstood easy fix" at one end and "dig up 45m2 of kitchen floor to replace underfloor heating" at the other.

There are a few variables and I'm not totally knowledgable about all of this.

Our system is a sealed one, most of it has been replaced in the last 5 years due to lots of building work and the boiler was replaced about 2 years ago for a WB. Our loft extension is 2nd floor (Ground, 1st, 2nd) in the loft, fed with plastic piping. The rad in the bathroom in this level needs bleeding every month or so and there's probably a 500ml of air coming out, or less.

The boiler pressure then has to be topped up from .5b to 1.5b and pulling the refill tap under the boiler takes a long time to fill up.

So, I am concluding that there's water coming out somewhere and air going in. Is this the only conclusion?

I have heard that fast pumps cavitate Hydrogen out of the water. The CH pump was on the highest setting for a while, now it's on 1.

I cannot see any leaks from rad valves above the floor. We cannot see any wet patches on any ceilings or floors or walls.

I recently borrowed a FLir Pro One Infra Red camera that attaches to the iPhone. This morning i traced the flooring in the kitchen and it's massively uneven, but I couldn't find a bloom of heat that looked like it shouldn't be there. I have no experience with viewing leaking heating pipes, so I'm not sure if this is correct.

What can I do to help diagnose the problem?

Can i catch the air from the radiator and measure it's volume? Do people do that? Is there an attachment for it or do i need to make one?

If I knew how much air, I would now how much leak per month and then I would know how much water I'm looking for.

I could also test that leaked air for Hydrogen; can I light it?

Then what? I could chop in to some ceilings that are old lathe/plaster that will come down anyway eventually, that might get me below some of the new rads that were put in.

Has anyone used a snake camera to look through a ceiling without taking the whole thing down?

After that, is my only other option to get a leak detection company in?

Many many thanks for any advice or input you can give!!!

Mr. Tickle.

To start you can isolate various parts of the system (boiler, UFH) and see if you still get a drop. Then you know where to start digging about.

Hi Dilalio,

Thanks for your reply.

Can I isolate the parts using the valves? The UFH is separate from the rest of house.

How do I isolate the boiler? Should I get my plumber in? Is it basically closing the Feed and Return and seeing if there's a leak inside the boiler somewhere? Would the water leak out of the physical boiler casing or is there a chance it would go elsewhere?

If I cut off the kitchen UFH, it'll be really really cold throughout winter! So I will try to get a more accurate figure of the quantity or frequency of bleeding the rad, which would give me a scale for the waiting!

Do people test the air for Hydrogen? Is it a plumbers trick to flick a lighter at the bleed valve? or is there some capture vessel available?

Thank you again!

Mr. T

What boiler do you have?

Is the system sealed with an external vessel and discharge?

There are various methods to try and pinpoint a potential leak.

If the boiler has its own discharge (PRV) you can isolate it from the rest of the system once pressurised (using the flow and return isolation valves underneath but be warned these can leak) after a 24hr period you can see if the pressure in the boiler has dropped = leak within boiler PRV, if it hasn't but then drops when you open valves back up, leak is in system outside of boiler.
You can isolate the UFH manifold and perform same test.

This all has to be done COLD with boiler OFF! So you will need to survive without boiler operating for 24hrs.

It's a WorcesterBosch Greenstar 29CDi Classic ErP.

It is sealed, there is no external expansion vessel. There is a discharge pipe on the outside of our house; is that the short copper pipe sticking out the wall?

So, i cool the system down to ambient, seal flow and return valves under the boiler and wait 24hrs. If the pressure has dropped, there's a leak in the Pressure Relief Valve inside the boiler?

Cheers!

I've just double-looked at the UFH manifold; I can't see how the water flows around it! It seems that all the CH water goes through it. The F/R to the boiler go into the manifold then out the other end. That way, it seems the water would always go around the UFH, but it doesn't.

So I'll have to rethink what I thought was going on there!

If the PRV was faulty, would it be sucking air in to the system?

What colour should the rad water be with inhibitor in it?

It shoots out milky-white, which could be bits of turbulence in the water. It clears quickly to a straw-yellow colour.

you are just confusing your problem , you have went from having a pressure drop to the UFH not circulating properly to what colour should you system water be, if you want the correct answers sort one problem at a time, and then start a new post for each of your other queries or you will never get the advice you seek

Thanks for your reply, too, Ian.

Sorry if the information is confusing! The previous poster asked for some additional information about my setup, so I was giving it. I also am not sure what the problem is; I'm asking for help building a diagnosis path, i suppose. I'm not sure what information is relevant or not.

The pressure drop in the system is a symptom, as is my refilling and pressurising the system to overcome that pressure drop. There is air in the system, I have read it could be several things, I was trying to offer information that could help.

I thought that if the water was dirty that it could be corrosion which causes hydrogen to build up. I also heard a hole in a rad that was high up could pull air in to the system. I also read that pumps can such air in to a pressurised system or that a duff valve somewhere could also do the same.

Thanks for the input! I'll wait for any other advice and try to stay on that.

Mr.T.