Central heating loosing pressure - Leak sealer

macadonald · 25 Sep 2013

Hi guys,

Very concerned as only 6 months ago, we finished a long slog of haveign downstairs renovated with an extension and new solid wood flooring Installed.

We have a combi boiler and over the last 3 weeks I have had to top up the system twice due to lost pressure. This is suggesting a slow drip leak somewhere. I know it's not comign from any of the upstairs radiators or pipe work as I'd see wet ceilings. This suggests it's downstairs and under the flooring.

From memory the builders plumber used plastic push fit piping with copper uprights to the rads.

I'll be gutted to have to start lifting the flooring and not even sure it can be doen easily?

Just wondering whether a product like Sentinel Leak sealer is an option? I know the prefferred solution will be to find the leak and sort it, but if there is an alternative, I'll give it a go.

Ta

Maca

gas112 · 25 Sep 2013

Turn the isolating valves off under the boiler for a couple of days see if pressure stays same so you know for definite its on the system

Jamesie · 25 Sep 2013

How much pressure are you loosing? I would physically check your rad connections, and connections to boiler just to be totally 100%. Also You should have a pipe running from boiler to outside, usually copper. Check theres nothing coming from there, its from the pressure relief valve, which may not be seated properly. If it is under your floor fingers crossed it isnt, i'd do it properly personally, as painful as it may be, as all that lovely expensive wood is gonna be like a massive sponge and will warp something chronic if wet underneath.

macadonald · 25 Sep 2013

Thanks to both for your responses. It's enough water loss to stop the combi from producing hot water and the pressure gauge is as low as it goes. I will follow advice and check the pipe that drains from the combi outside. Would almost be relieved if that was the problem (I think)..

Definately not leaking from any of the visible connections onto rads. Done a double check.

The technical guys at Fernox, said their F4 leak sealant is designed for that and worth a go before bothering to lift any flooring. We are suspended timber flooring, so the leak just dissapears.

macadonald · 25 Sep 2013

Hi Jamesie,

Just curious, but your point about the pressure relief possibly not being properly seated, could this result in a slow leak, 1 week between havign to recharge the system?

Ha, as I am typing this I think I have just remembered that when the boiler was installed 3 yrs ago, the pipe work for what you are referring to goes down a stud wall and is plumbed into the waste from the bath. All hidden though. I guess I could cut the pipe at the boiler and check there?

Jamesie · 25 Sep 2013

That maybe your condensate drain usually 22mm plastic from the boiler, and sometimes the 22mm is fitted into inch and 1/4 with reducer. What boiler is it out of curiosity?
Yeah if the valve aint seated fully, its gonna evantually remove all system pressure, think of a balloon with a tiny hole in it.

macadonald · 25 Sep 2013

It's a Vailant Eco something...

When you say 'its gonna evantually remove all system pressure', is eventually more rapid than a week.

Sounds like it might be worth giving this sealant a go? Haven't heard of any definate NO's to the product. I will still check what you said first.

Thanks

andytw · 25 Sep 2013

1. It is worth checking that your expansion vessel is charged.

2. Fill your sysem to the desired pressure when cold (1 bar ?0 and then note what pressure does the gauge go to when the heating is on and hot ?

andytw

Jamesie · 26 Sep 2013

When you say 'its gonna evantually remove all system pressure', is eventually more rapid than a week.

It would depend on how much the valve would be open i guess.

I suppose you have nothing to loose by using the sealer, and could save you a shed load of work if it works. and i suppose the pressure gauge will be your indicator wether it's worked or not. fingers crossed mate it does the trick.

Agile · 26 Sep 2013

andytw said:
1. It is worth checking that your expansion vessel is charged.

andytw

How do you expect a DIYer to do that safely on an Eco Something?

Its not a DIY job.

We don't seem to have any proper information about the amount of the leak.

How long between 1.5 bar down to 1.0 bar both measured with the system cold?

Tony

macadonald · 26 Sep 2013

All,

Thanks for the responses. re information about the leak, all I can say is what I said in my post. The pressure was being lost over 2 weeks and then 1 week and yesterday evening I had lost it after 1 day. No sign of the leak on any ceilings or joins, so I assume it is under the floor.

After gettign home last night and not having hot water after charging it in the morning, I decided to get the Sentinol Leak Sealer rather late yesterday eveing. Drained the system enough to get into the circulating part of the system and poured the stuff into the top of the bathroom towel rail rad, which made sense from an access point of view. Top it all up and repressurised and touch wood, my wife confirmed about an hr ago that we still have hot water. I will get into the loft tonight and check the pressure gauge.

Out of interest, what advice does anyone have for the temp settings on the boiler for the central heating and also the pressure to have the system at when cold for eg? My boiler isn't preceise on pressure, it has a green, grey and red section.

Many thanks all.

Maca

Agile · 26 Sep 2013

Now I can see why you have not been giving us information on the pressure. Its because the boiler is in the loft and I suspect access is not good!

I would never recommend using that leak sealer in a modern boiler.

How do you know its not being discharged from the pressure relief valve vent?

Tony

macadonald · 26 Sep 2013

Agile,

Could have done with you saying that earlier, but too late now anyway. I spoke to the technical support at Sentinel and Fernox and both confirmed it can be used with the boiler and type of fittings. The stuff is designed to work with pressure release valves and the particles small enough to flow through any valves and or filters.

Cannot say much more than that, apart from it appears to be working. If it fails, I will resort to getting the leak repaired, where ever it is.

What do you mean "How do you know its not being discharged from the pressure relief valve vent?"

So what if it is? It's one litre of the stuff in an entire system. If some was released after the leak was fixed, would that matter.

Yes you are correct in the I am not 'Agile' enough to easily jump into the loft very often

Agile · 26 Sep 2013

Its the boiler makers who would give their views on adding leak sealer not the ( biased ) people who sell it.

When a boiler is fitted in a loft there are minimum standards which include lighting, flooring and particularly a fixed ladder ( often a retractable loft ladder ).

But certainly NOT steps which require gymnastics to get into the loft.

What I was meaning about the pressure relief valve discharging is that could well be where your loss of water was occurring.

So will it if the expansion vessel is not correctly charged. But that is NOT a DIY job as its housed inside the sealed combustion area.

Tony

macadonald · 26 Sep 2013

Thanks Agile,

Re standards for boiler in loft, they are all there, but still an effort

If I have further problems I guess the next best is to get your items checked.

Probably the best thing I could do right now is to take out boiler insurance with BG or Vailant. At least if somethgin is on it's way out I might be covered then.

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Central heating loosing pressure - Leak sealer

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