Hi, everyone. In the past few days my primary (smaller) feed tank has started to overflow hot water when I run hot water. Investigating in the loft, I found hot water coming in through the vent pipe. Also, running the cold water (e.g. flushing or using kitchen tap) makes cold water flow in at the float valve (even though it\\\'s been replaced and adjusted) to give the same overfilling. Baxi WM552 gas boiler, Wilo Gold 50 c/h pump, \\\"gravity\\\" hot water; system powerflushed 30 months ago. Any help appreciated.
Primary tank overflow
- Thread starter powerjohn
- Start date
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try putting floer in the header tank this will sort things out
do educate the great unwashed
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gerrout of it its a back boiler in a case on the wall
John ignore "floer".
However somethings strange with initial post. In no particular order:
You spoke of smaller tank which is Feed and Expansion tank to CH. Much bigger tank is Cold Water Storage Tank.
Cold tap in kitchen should be mains fed so running it should not activate float valve in CWSTank. Flushing toilet or use of any hot taps or cold bath taps will take water from CWSTank and this will activate floatvalve.
Hot water from vent on F&E tank is due to restriction in circulation in CH possibly due to all rads being closed off or a sludged up system. This should not cause overflowing as water should circulate back down feed pipe from bottom of the tank. However if feed pipe is blocked this may not happen and system will gradually empty as water overflows out.
Another possibility is that float valve is set at too high a water level when system is cold and as water heats/expands it overflows. Water will be replenished when system cools through float valve. Neither scenario is very desireable.
Couple of things to try:
Bail out F&E tank with system cold and set float valve so that it closes when water is a couple of inches above feed tank. This will give room for expansion and solve second possibility above.
Tie up floatvalve and drain a bucketful of water from a drain off point in your system. If level in F&E tank doesn't drop you have a blocked feed pipe. Need to drain system cut feed where it meets main CH circuit, clean it out and rejoin feed with compression fitting.
A further problem which causes F&E tank to overflow is where you have a fault in the indirect coil in the hot water cylinder allowing water to pass into the CH system causing tank to overflow. Replacement of cylinder is solution in this case.
However somethings strange with initial post. In no particular order:
You spoke of smaller tank which is Feed and Expansion tank to CH. Much bigger tank is Cold Water Storage Tank.
Cold tap in kitchen should be mains fed so running it should not activate float valve in CWSTank. Flushing toilet or use of any hot taps or cold bath taps will take water from CWSTank and this will activate floatvalve.
Hot water from vent on F&E tank is due to restriction in circulation in CH possibly due to all rads being closed off or a sludged up system. This should not cause overflowing as water should circulate back down feed pipe from bottom of the tank. However if feed pipe is blocked this may not happen and system will gradually empty as water overflows out.
Another possibility is that float valve is set at too high a water level when system is cold and as water heats/expands it overflows. Water will be replenished when system cools through float valve. Neither scenario is very desireable.
Couple of things to try:
Bail out F&E tank with system cold and set float valve so that it closes when water is a couple of inches above feed tank. This will give room for expansion and solve second possibility above.
Tie up floatvalve and drain a bucketful of water from a drain off point in your system. If level in F&E tank doesn't drop you have a blocked feed pipe. Need to drain system cut feed where it meets main CH circuit, clean it out and rejoin feed with compression fitting.
A further problem which causes F&E tank to overflow is where you have a fault in the indirect coil in the hot water cylinder allowing water to pass into the CH system causing tank to overflow. Replacement of cylinder is solution in this case.
Some good ideas there, jobloggs - thanks! I'll try them asap. I suspect that the cold overflow was being caused by high water level in the F&E tank flooding the float valve and not letting it close. Rads are all open and system was powerflushed about 30 months ago; all rads heat well, so I think sludging is out. You're not the first to mention a faulty heating coil, but I do hope you're wrong on that, as it will use up all my cocoa money for years!
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