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Underground Heating Pressure Loss.


danny
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due to the fall in temperature we put the heating on. I noticed that the pressure gauge which normally stays at 1.5bars falls very quickly to zero within the space of an hour. It would appear that I have a leak. We had the boiler serviced two weeks ago and a few leaks and pipes were replaced. We see no evidence of water in, around or under the boiler. I have opened up the system and can see no leaks or evidence of water. I have taken out the two pipes coming from the boiler system into the house and examined them in detail and nothing.

The underground system in the house is broken down into zones, such as SDB, Sejour chambre etc. , what I am currently doing is turning off each zone and then checking if the pressure continues to drop, if it does I then turn off the next zone and reset the pressure at 1.5bars.

Can I assume that if i do the above and the pressure continues to drop that i can conclude that their is no leak in the underground pipes in the house and the fault lies elsewhere.

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Are you turning off only the supply valve to each zone? If so, the return side is still open to the system and any leak will not be isolated.

If you also have valves to shut off the return side, you can isolate each zone completely, but if you do this you should disconnect the pipe on the zone side of the valve. If you don't do so, the water trapped in the zone may contract or expand, possibly causing either the pipe in the zone to collapse or the pipe or joints in the zone to burst.

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Finally the experts !! have arrived. They have changed two "manometres" gauges. Before leaving they said that the pressure would keep falling for 3 days and that we would need to repressurise the system. They also said that the temperature gauges would rise initially and then fall back to their normal range of 25 to 30. They alos said that a lot of air was in the system.

That was 3 hours ago, so far the pressure falls 1 bar every 70 minutes and the temperature gauges are at 40c and not falling. Is this normal or have we been told lies.

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You either have a hell of a lot of air in the system or you have a leak

As professionals I would have thought they would have left the system purged and free of air

My opinion you have a leak

As water is not compressible you need to loose very little for the pressure to drop

If there is no leak and the system has been proerly vented to remove the air the pressure would only fluctuate slightly due to changes in temperature

The temperature of the water is a function of the system controls and nothing to do with the pressure loss

It is time consuming but relatively simple for the installer to disconnect each underfloor circuit from the manifold and individually pressure test them, this should be done to 4 bar

This would indentify a leak in the underfloor heating and identify the individual circuit

I suggest you get them to come back and try again

Le Plombier
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[quote user="danny"]Finally the experts !! have arrived. They have changed two "manometres" gauges. Before leaving they said that the pressure would keep falling for 3 days and that we would need to repressurise the system.[/quote]

Long enough to get your cheque cashed?

Frankly, their tale sounds like rubbish

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Can I tap into your knowledge bank again. Over the past three days we have monitored the pressure. Basically every time we set the pressure at 2 bars one hour later it has fallen 1 bar. We have done this 22 times. We have also purged the air from all of the manifolds and nothing has changed.

This morning we noticed that water was coming through the wooden ceiling. Upon inspection it was coming from the air conditioning unit called "Aerlec" this is just for cold air. I took the frame off and their is three pipes going into the system. Two of them are red and one is blue. It would appear that one of them the blue one is some form of overflow pipe. The plastic section connecting it to the the blue pipe has degraded.

So far today we have taken 10 to 15 litres of water out of the system. It is a constant drip. The system has been deactivated and it is not plugged into the electrical system, nor has it been for sereral months.

We have a call in for the heating engineer and the plumber for tomorrow but are not expecting a rapid response. I guess it will take several days.

We turned off the water in the house to see if we could stop the flow of water, however whilst we have no water for the washing machine, dishwasher, taps, both hot and cold and toilets the drip continues unabated.

Is it possible that the air conditioning system is intergrated into our underground heating system and this is the reason for the constant pressure fall.

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Strange, possibly more info needed

You seem to be describing an air conditioning unit which I would expect to have three pipes, two refrigeration lines from an external condensing unit and a condense drain

I would not expect any connection to the heating system

But then you would only get water in the condense drain when the unit was running and cooling

Are the red and blue pipes PER plastic pipe?

If they are can you be sure the unit you describe provides cooling,and is the cooling a cold air supply or cooling of the undefloor circuits

Was all of this done as a single installation or separately for the under floor and air cooling?

What you describe at the moment makes no sense to me

Le Plombier
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Thanks for the response. Just had the plumber around and got him to disconnect the air conditioning unit from the manifold. Apperently the unit is connected to one of the two manifolds that operate the underground system. A leak had developed in the unit but was not seen by the heating people as the overflow pipe was taking the water away. The leak only became visible because I kept repressurising the system and the overflow pipe broke and the water leaked out.

Now that it has been disconnected the system is operating at 100%.

Thank you for all of your advice. Right from the start you said we had a leak and you were correct.

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