another overflow !

[furryneddy]

Hi - happy Halloween all,
got an "intermittant" overflow on CWST four floors up in a small hotel - boiler is on the ground floor and is an old stelrad ideal Mexico it's F&E tank is above the boiler on the ground floor. the boiler does not supply heating for the hotel and supplies two small rads and a towel rail in the owners flat which is pumped, the hot water is heated in the cylinder which is connected through the wall and has no pump on this side so I assume gravity fed heated, this supplies the hotel and living quarterts with hot water. There are only electric showers in the rooms and all heating in the hotel is electric storage. I have checked for mixer/thermostatic valves and there is only one which is the kitchen tap. The owner says that when he runs it sometimes the water is hot then cold and then hot again . I held the cold feed pipe to the cylinder whilst the hot in the bathroom was run and sure enough the water is cold but once shut off the pipe very quickly starts to warm up again and if left five mins soon reaches the same temp as the tank warm water can be felt coming in the CWST at the top of the house and is obviously causing the overflow. what I dont understand is is if there is a hole in the coil how is it managing to push water up 4 floors when the expan tank is on the ground floor? I have read other posts on this kind of problem and I know logic tells me that what I have described is "impossible" or am I missing something ? I would appreciate any help on this as its keeping me awake at night thinking about it

 

[stevetheplumber]

Hi - happy Halloween all,
got an "intermittant" overflow on CWST four floors up in a small hotel - boiler is on the ground floor and is an old stelrad ideal Mexico it's F&E tank is above the boiler on the ground floor. the boiler does not supply heating for the hotel and supplies two small rads and a towel rail in the owners flat which is pumped, the hot water is heated in the cylinder which is connected through the wall and has no pump on this side so I assume gravity fed heated, this supplies the hotel and living quarterts with hot water. There are only electric showers in the rooms and all heating in the hotel is electric storage. I have checked for mixer/thermostatic valves and there is only one which is the kitchen tap. The owner says that when he runs it sometimes the water is hot then cold and then hot again . I held the cold feed pipe to the cylinder whilst the hot in the bathroom was run and sure enough the water is cold but once shut off the pipe very quickly starts to warm up again and if left five mins soon reaches the same temp as the tank warm water can be felt coming in the CWST at the top of the house and is obviously causing the overflow. what I dont understand is is if there is a hole in the coil how is it managing to push water up 4 floors when the expan tank is on the ground floor? I have read other posts on this kind of problem and I know logic tells me that what I have described is "impossible" or am I missing something ? I would appreciate any help on this as its keeping me awake at night thinking about it

your right its impossible for the coil to be ferforated as it would be pouring out of the f and e tank id look again at the kitchen tap if its not bi flow then it should have nrv's on it

 

[david williams]

is there any control over heating the cylinder,if not it may be that the cylinder is so hot it is convecting hot water up the cylinder cold feed into cwsc.

 

[furryneddy]

Hi dave - no there is no control other than the thermo on the front of the boiler which is quite old. Did wonder if its heating up so much that it would be able to push water up that distance ?

Hi thnx for your reply - the taps quite old and has been in a while is it likely to fail with age?

 

[buffy27]

Hi - happy Halloween all,
got an "intermittant" overflow on CWST four floors up in a small hotel - boiler is on the ground floor and is an old stelrad ideal Mexico it's F&E tank is above the boiler on the ground floor. the boiler does not supply heating for the hotel and supplies two small rads and a towel rail in the owners flat which is pumped, the hot water is heated in the cylinder which is connected through the wall and has no pump on this side so I assume gravity fed heated, this supplies the hotel and living quarterts with hot water. There are only electric showers in the rooms and all heating in the hotel is electric storage. I have checked for mixer/thermostatic valves and there is only one which is the kitchen tap. The owner says that when he runs it sometimes the water is hot then cold and then hot again . I held the cold feed pipe to the cylinder whilst the hot in the bathroom was run and sure enough the water is cold but once shut off the pipe very quickly starts to warm up again and if left five mins soon reaches the same temp as the tank warm water can be felt coming in the CWST at the top of the house and is obviously causing the overflow. what I dont understand is is if there is a hole in the coil how is it managing to push water up 4 floors when the expan tank is on the ground floor? I have read other posts on this kind of problem and I know logic tells me that what I have described is "impossible" or am I missing something ? I would appreciate any help on this as its keeping me awake at night thinking about it

whats the craic.
ya if the f & e is lower than the cwst then it will overfill in the case of a hole in the coil.in your case that cwst is making up some nice head if it's 4 stories up. [1 bar every 10 meters.] point being it would show on the f&e and not the cwst in your case.[what exactly is the cylinder..single coil ..is it only the one boiler doing rads and hw.]
the other thing mentioned in maybe about heat creep /or expansion ,where hot water rises up the cold water feed..... is the tank overflowing much or just a little. [ this heated water has only one outlet in a kitchen tap and may be heated constantly in the day???]
maybe tha expanding water has not the room in the tank to expand [maybe the ball cock was replaced and sits higher or closer to the overflow pipe??/

disregard what i have said above please. .. [the hamster is back on the wheel in my head now...] either the expansion on the dhw is blocked or the cold is forcing the hot back..in the kitchen tap.. end of story...too much beer last night.

 

[furryneddy]

Hi buffy Thnx for your reply - will be back to that job early part of the week so will isolate tap and check expansion pipe - anyone no a good way of checking if the expan pipes blocked it is realllllllyyyyyyy veryyyyyy long

 

[stevetheplumber]

Hi buffy Thnx for your reply - will be back to that job early part of the week so will isolate tap and check expansion pipe - anyone no a good way of checking if the expan pipes blocked it is realllllllyyyyyyy veryyyyyy long

turn of the cold feed as soon as you start to drain submerge the open vent in a glass of water if its not blocked it will suck the water from the glass probably the system wont drain at all if no taps are opened

 

[buffy27]

turn of the cold feed as soon as you start to drain submerge the open vent in a glass of water if its not blocked it will suck the water from the glass probably the system wont drain at all if no taps are opened

can u explain this better ..please..thanks man..sounds clever //

 

[helpsy]

can u explain this better ..please..thanks man..sounds clever //

I think I understood it to mean:-
If cold feed from CWSC shut off and no blockage in vent pipe when you drain cylinder down if you had a glass full of water placed directly on the end of the vent pipe it would create a vacuum drawing out the water from the glass.If there was a blockage in the vent pipe then the water would stay in the glass as there would be no vacuum at the glass.

 

[stevetheplumber]

I think I understood it to mean:-
If cold feed from CWSC shut off and no blockage in vent pipe when you drain cylinder down if you had a glass full of water placed directly on the end of the vent pipe it would create a vacuum drawing out the water from the glass.If there was a blockage in the vent pipe then the water would stay in the glass as there would be no vacuum at the glass.

that exactly what i meant to say you can use this idea to check if a main is leaking put the glass of water over the spout of the kitchen tap and turn of the main if theres a leak it will suck the glass dry as the pipework empties from a leak below ground