F & E Tank Question

[kev999]

Does water in the F&E Tank on the C/Heating evaporate?
The reason I ask is I have isolated the water going into the tank because plumbing work was being done.
I have kept an eye on the tank level because I thought maybe it was losing water.
Anyway in 4 days the water level has gone down about 30mm in a 25 Gallon Tank.
This is with the system full and bleed, Also I have not used boiler for heating or water since I filled it up.
I'm hoping this may be due to natural evaporation, or I'm I clutching at straws?
I have no visible leaks around the tank or around rads or pipework that can be seen. The thing that does worry me is that the pipes down stairs are buried under a concrete screeded floor.
What is the best way to check if I have a leak?
I have just had a nw Boiler installed and the pipework has been changed from a gravity feed to a fully pumped system.

 

[gas4you]

Yes it does evaporate but not at this rate You would be lucky to lose this amount after a long hot summer.

You need to check once again for leaks.

 

[kev999]

Thanks for the answer, I hate to say it but I think I may have a leak somewhere under the floor. I have seen no signs of a leak, damp floor etc.
Do you think I may be able to get something like this done on house insurance? I have full accident cover.

 

[twgas]

check your policies, a lot of variation in cover but in my experience anything damaged by water is covered but the water producer, be it washing machine, tank, boiler etc. is not usually covered.

 

[Softus]

I have isolated the water going into the tank because plumbing work was being done.

I have a hunch that the plumbing work may be of some relevance. What was/is it?

I have kept an eye on the tank level because I thought maybe it was losing water.

For how long has it been losing water?

Anyway in 4 days the water level has gone down about 30mm in a 25 Gallon Tank.

WTF are you doing with a 25 gallon F&E cistern?

I'm hoping this may be due to natural evaporation, or I'm I clutching at straws?

Straws.

What is the best way to check if I have a leak?

Wait for longer, or dig the floor up.

Or turn on the system and use a thermal imaging camera to find the hot spot.

 

[TicklyT]

Feed & expansion tanks are usually much smaller than 25 gallons. They are usually about 4 or 5 gallon nominal capacity, and usually set up so there is only a couple of inches of water covering the outlet.

They probably only hold a couple of gallons of water when operating normally.

If the F&E is filled to just below the overflow level with the system cold, it will lose water through the overflow when the system heats up due to expansion of the water.

A 25 gallon tank is more likely cold water storage for the hot water system. Opening any hot tap, intentionally or otherwise, will cause the level to drop if it isn't replenished by the float valve.

Don't rely on the gate valve usually fitted to isolate the hot water cylinder to give a 100% seal. They can let a bit of water dribble into the hot cylinder when closed. If the cylinder has been drained, it will probably be a few days before it re-fills enough to become a problem.

 

[kev999]

Thanks for the replys.
I replaced the F&E Tank myself why the boiler was down, the old metal tank had a lot of scale in it so I thought I would replace it.
It is the correct tank, I have other larger tanks for the hot water.
The old one was about 20 gallons, I was not sure if I could get away with a 4 gallon tank becuase it is quite a large system, so to be on the safe side I replaced with as close as I could find.
Plumbing work done before I noticed water droping was I had a new boiler fitted and had the pipework changed from a gravity feed hot water system to a fully pumped system. I also had the upstairs and downstairs put on seperate zones.
I really have not hardly had the boiler on becuase of the weather.
The other thing I have just noticed is that I just tried the downstairs heating on and now I have noticed that the return pipe (Oposite end to the TRV) is getting hot before the Flow pipe (The end with the TVR).
I'm not a plumber but that does not sound correct to me.
Is that a big Mistake by the Pumber?

 

[kev999]

Any body got any idea about the flow and retuns thing in particular?
Thanks

 

[Blasphemous]

I have isolated the water going into the tank because plumbing work was being done.

I have a hunch that the plumbing work may be of some relevance. What was/is it?

I replaced the F&E Tank myself why the boiler was down, the old metal tank had a lot of scale in it so I thought I would replace it.
It is the correct tank, I have other larger tanks for the hot water.
The old one was about 20 gallons, I was not sure if I could get away with a 4 gallon tank becuase it is quite a large system, so to be on the safe side I replaced with as close as I could find.

Hmmm, I'm with softus on this one!

I have just noticed is that I just tried the downstairs heating on and now I have noticed that the return pipe (Oposite end to the TRV) is getting hot before the Flow pipe (The end with the TVR).
I'm not a plumber but that does not sound correct to me.
Is that a big Mistake by the Plumber?

Most TRVs are multi directional so shouldn't make any difference. Do BOTH pipes get hot eventually?

 

[Rico99]

Kev,

Provding the TRVs are bi-directional it doesnt matter which end they are on.

They do usually get put on the flow as this tends to be the most accesible end of the rad.

Rico

 

[kev999]

Thanks for the replys.
The thing about the flow and return pipes is that the TRVs were on the correct ends before I had the pipework changed for the new boiler.
Is it possible for the flow and return pipes to be connected to the boiler wrong?
Why should the original return pipes get hot before the flow pipes?
Thanks

 

[Softus]

I replaced the F&E Tank myself why the boiler was down, the old metal tank had a lot of scale in it so I thought I would replace it.
It is the correct tank, I have other larger tanks for the hot water.
The old one was about 20 gallons, I was not sure if I could get away with a 4 gallon tank becuase it is quite a large system, so to be on the safe side I replaced with as close as I could find.

Enough of this vague bullshit - please list the components in your system, including quantity of radiators and floors in the house, boiler make/model, and size of cylinder.

Next, please explain why you replaced the F&E cistern when you had plumbers in the house working on the heating system. Why did you not take their advice, better still ask the plumbers to do the plumbing work?

Next, please explain why you isolated the supply and filled the cistern when other people were working on the system.

Next, please explain how on earth you expect to get any warranty from the plumbers you engaged when you're cocking up their work.

That should keep you busy for long enough to take your mind of the complete irrelevance of the TRVs.

I have just noticed is that I just tried the downstairs heating on...

Why have you filled the system without a corrosion inhibitor?

Or, if you added a dose of inhibitor, why did you do that before finding the leak, given that you'll have to throw it away immediately?

 

[kev999]

Enough of this vague bulls**t - please list the components in your system, including quantity of radiators and floors in the house, boiler make/model, and size of cylinder.

I have a worchester greenstar oil condensing utility boiler fitted 25/32 . I have 24 Rads on it, 11 downstairs 13 upstairs. (Sounds like a lot of rads but I will only have half of them on at any time, My Cylinder is approx 1100mm high.I also have a Groundfoss Pump and 3 zone valves by the boiler and 2 RF Room Stats
The plumbers came in and put the new boiler in and at the same time zoned upstairs, downstairs and hot water. It used to be a gravity feed hot water system, they changed it to a fully pumped system

Next, please explain why you replaced the F&E cistern when you had plumbers in the house working on the heating system. Why did you not take their advice, better still ask the plumbers to do the
plumbing work?

I replaced the F&E Tank between the plumbers coming in to quote for the boiler work and them auctually doing the job. The tank was in before the plumbers came in. Apart from the fact that the Tank may be Large I'm 100% Happy with the tank, that is not my probem, it was just a straight change over with only a little bit of pipework that I could do myself. I really needed to keep this job done on the plumbers labour, that is why I did it myself.

Next, please explain why you isolated the supply and filled the cistern when other people were working on the system.

First I only isolated the supply ready for the Plumbers to work on the Boiler etc, I only refilled it when they told me to after they had fitted the Boiler and finished thier pipework. The Boiler was not fired up that day because it was late and the electrics were not finished. It was only then I isolated the supply for piece of mind because thy were not returning for 5 days. The night before they returned I went to turn the suppy back on and that is when I noticed the water drop in the Tank. I have been keeping an eye on it since and it has been dropping steady, it dropped about 40mm in 4 days (25 gallon tank).. The other night I ran the downstairs heating for half hour then checked the tank and it had drop 20mm more just in that half hour, the next night I checked the tank and it was nearly empty and the boiler had not been on at all.

Next, please explain how on earth you expect to get any warranty from the plumbers you engaged when you're cocking up their work.

I have done no work after the plumbers have finished, all I did before they came was install the new tank and fit TVRs to the rads.

That should keep you busy for long enough to take your mind of the complete irrelevance of the TRVs.

The reason I mentioned the return getting hot before the flow is because it was not like this before the plumbers work was done.

I have just noticed is that I just tried the downstairs heating on...

Why have you filled the system without a corrosion inhibitor?

Or, if you added a dose of inhibitor, why did you do that before finding the leak, given that you'll have to throw it away immediately?

I have not put inhibitor in yet I'm waiting to make sure I don't have a problem, then I will do it.[/quote]

I have been told maybe the system still has a lot of Air in it and it is settling down. I have bleed the rads, would the tank level drop steadily until all the air is out?
My worry is that downstairs my Central heating pipes go under a concrete floor, I'm concerned that I may have a leak under the concrete and that is where I'm losing the water.
I can see no evidence of a leak.
I will be phoneing the Plumber Monday to get his advice, I just wanted to try to work out where the water is going before I contact the Plumber.

 

[D_Hailsham]

The thing about the flow and return pipes is that the TRVs were on the correct ends before I had the pipework changed for the new boiler.
Is it possible for the flow and return pipes to be connected to the boiler wrong?
Why should the original return pipes get hot before the flow pipes?
Thanks

The connections on your new boiler are on the opposite side from your old boiler. My guess is that the plumber found it easier to connect them the other way round. Provide the pump is pumping away from the boiler, it does not matter which pipe is the feed and which the return.

You say you have new TRVs. Most new TRVs are bidirectional, so they can be fitted to either flow or return. Just check that they have a double-headed arrow on them.

With a system as big as yours you may still have air in it. Open all Lockshield valves completely (make a note of how many turns are required so you can reset them later ) and remove all TRV heads. Then lock each zone valve in the open position (usually marked MAN).

Now bleed each rad with the water cold.

When that is done, set the zone valves to AUTO and turn one thermostat up so its zone valve is open. Now run the system while you watch the water level in your F/E tank (The level when cold should be about one or two inches above the feed to the CH system. If it is any higher, the ball valve needs adjusting to lower the ball.)

If the level does not change, then that zone is not leaking.

Turn down the stat and repeat for each of the other zones. This will identify which zone, if any has problems.

When you have sorted the "leak" out, you will have to reset the lockshield valves, which should be easy if you wrote down how many turns you opened the valve

 

[kev999]

Thank you for your reply, I will try what you have said.

The level when cold should be about one or two inches above the feed to the CH system.

I'm not sure what you mean by one or two inches above the feed to the C/H system.
Do you mean one or two inches above the outlet pipe on the F&E tank, so the f&E Tank should be near empty?
By the way my F & E Tank is raised up about six foot above the hot water tanks in the loft, just thought I would mention this.