Expansion tank evaporation

mloc123

Is it normal for an open heating system to lose water through evaporation from the expansion tank?

I am pretty sure my system is, would putting a cover on the expansion tank help reduce this?

freddyuk

The Feed and Expansion tank is just that - it feeds mains water into the system via a ballcock valve. Any evaporation is replaced automatically. Why do you think it is a problem?

mloc123

freddyuk wrote: »

The Feed and Expansion tank is just that - it feeds mains water into the system via a ballcock valve. Any evaporation is replaced automatically. Why do you think it is a problem?

I have the ball cock tied up at the moment, new one ready to go in once I have time, but the level has dropped while it is tied up.

I have refilled it manually a couple of times now as the level has dropped inches. Leak wise, I can't spot any in the system.

I want to put inhibitor in the system after sorting the ball cock, so I want to limit an loss. The return/vent pipe returns warm water when the boiler is on (I understand this is from a poorly design system). This means the water in the tank is warm and there is visible evaporation, I am think a cover would help?

shane0007

You have a leak.
I had one today. We were zoning a system and when draining the system, the water kept flowing and flowing. Checked attic and cwst was continuously filling. The coil in the cylinder was split.

TPM

mloc123 wrote: »

I have the ball cock tied up at the moment, new one ready to go in once I have time, but the level has dropped while it is tied up.

I have refilled it manually a couple of times now as the level has dropped inches. Leak wise, I can't spot any in the system.

I want to put inhibitor in the system after sorting the ball cock, so I want to limit an loss. The return/vent pipe returns warm water when the boiler is on (I understand this is from a poorly design system). This means the water in the tank is warm and there is visible evaporation, I am think a cover would help?

If there is a solid fuel boiler in your system you must not use it with the ball cock tied up.

when you say "visible evaporation" are you seeing steam? It shouldnt be getting hot enough to cause this, if it is you need to get it looked at.

I agree with shane that you have a leak you wont really loose enough through evaporation to empty the tank. the coil in the cylinder is definitely worth checking

WestWicklow1

Pump set too high?

shane0007

WestWicklow1 wrote: »

Pump set too high?

How would pump set too high lose water from the f & e tank?

WestWicklow1

shane0007 wrote: »

How would pump set too high lose water from the f & e tank?

mloc123 said....

"This means the water in the tank is warm and there is visible evaporation"

I had the problem of hot water overflowing into the f&e tank. I turned the pump from it's highest setting of 3 down to 2 and the problem went away.

shane0007

That is a pitching/pump over issue as your osvp is in front of the positive side of the pump, whereas it should be in the negative side ideally. It would still not cause the f & e tank to drop in water level.

jayceegoodmark

I think you will have to alter your system, a pitching vent pipe can cause your boiler and rads to rust very quickly. The drop in level in header tank could be due to the temperature of water at different times.

mloc123

Issue sorted since. Raised the vent pipe and lowered the water level in the tank, no longer pitches... unless I close of some of the rads but that is a job for another day.