A poser for you plumbers

[POPEYE]

I'd like to see wot your diagnosis is???
got called to the indian rest in bosham last night, (do the occaisional jobby for the bloke) theres "hot" water flowing from the storage tank overflow, the system is a conventional one, tanks, cylinder, three port, pump and boiler
(ancient) there was a gas board plumber there as well and he's never seen owt like it, the cold feed to the cylinder is hot and the hot draw off pipe at the top is cold but warms up when ya run the hot taps,

i reccon its a perforated coil in the indirect cylinder (which is also old, and big)
and if i remember rightly the f&e is sited higher than the storage tank, so i think it's back feeding cold water from the f&e, backfeeding up to the lower storage tank and overflowing!
i've had this a couple of times in the past after replaceing the ball valve (always first step of an overflow) but these were in houses not commersial,
anyway the expert from british gas is going back today to check it out, i dont touch his (or any central heating boilers as i aint corgi or acops) so we'll see what he says, but what do you think, personaly i cant see any other reason for the system going into reverse,

[BUSHWHACKER]

Change the rad cap.

[POPEYE]

Change the rad cap.

you mean rad "valve"

[BUSHWHACKER]

you mean rad "valve"

Nope, rad cap, it's always the rad cap.

[MattF]

Walked straight into that one Ian.

[tintin]

I agree with you Popeye, most likely cause = leaky coil on the secondaries.
Alan
( but then WTF do i know????)

[Tiger]

If the coil is leaking surely you would see contamination in the hot water at the taps, is it hot water coming out of the expansion, is the cylinder stat knackered. Unless the the f&E tank is considerably higher say 2m plus wouldn't of thought it would be pushing the cold water tank back if coil gone.
You would of hered the f&e tank filling up?? Or knakered mixer tap sending mains cold water up the hot water tap. (had that one before)

[POPEYE]

I did'nt go into the loft, no ladder and a torch with nr flat battery, and that was the gas guys, you may well be right! mixer tap bugger'd but i'm more inclined to the coil being at fault, only way to check i guess is disconnect the hearter pipes to the coil, drain the cylinder and leave the drain cock open, plug up one heater conn and run mains to the other, if the coils gone it'll run out the drain cock, if not the mains hose will swell up or blow off, anyhoo my tenners on the coil,

BTW this has been going on for a week! his staff only just told him sending him into a hissing fit, i think they were getting a boll0king in indo or urdo
so any contamination as long since flushed through

[mckirdy-services]

Rip it all out and start again

[Tiger]

Thats definately a british gas approach £6k +

[joker??]

burp it then use toyota red coolant
have a good flush first

[_cj_]

i agree - most likely is coil failure -just tie up the ball valve to cold cistern and if it keeps filling up then it must be comming up the supply to the cylinder

only other thing i could think of was cylinder overheating maybe vent pipe isnt high enough over the cistern so its pushing the water up and over the vent

most probably coil failure though

regards,

alex

[bu5hwack3r]

I'd like to see wot your diagnosis is???
got called to the indian rest in bosham last night, (do the occaisional jobby for the bloke) theres "hot" water flowing from the storage tank overflow, the system is a conventional one, tanks, cylinder, three port, pump and boiler
(ancient) there was a gas board plumber there as well and he's never seen owt like it, the cold feed to the cylinder is hot and the hot draw off pipe at the top is cold but warms up when ya run the hot taps,

i reccon its a perforated coil in the indirect cylinder (which is also old, and big)
and if i remember rightly the f&e is sited higher than the storage tank, so i think it's back feeding cold water from the f&e, backfeeding up to the lower storage tank and overflowing!
i've had this a couple of times in the past after replaceing the ball valve (always first step of an overflow) but these were in houses not commersial,
anyway the expert from british gas is going back today to check it out, i dont touch his (or any central heating boilers as i aint corgi or acops) so we'll see what he says, but what do you think, personaly i cant see any other reason for the system going into reverse,

Yep, could be failure in the heat exchanger inside the HW cylinder, and I agree with Tiger, unless F&E tank is considerably higher than CW storage tank, the head wouldn't be sufficient to create backflow. The system sounds poorly designed, and I never use 3 port motorised valves, rather 2 x 2 port valves, so this would be something I would check also. Theres also the possibility of it 'pumping over' particularly if the system is old and furred up with limescale, so check setting on pump and turn down if necessary. I would also check the feed from the F&E tank, as sometimes blockages occur at the filling 'T' due to turbulence. (where the air seperator is if one is fitted) My course of action would be drain down, run for a week with sludge remover, drain down and replace HW cylinder if you establish its the heat exchanger, install new cylinder, refill with inhibitor added, bleed, charge accordingly, go to the pub

Let us know how you get on.

[nero279]

i'd hope it's sorted by now, in 3 months he's going to have lost a lot of hot water if it isn't!

[RodLeach]

i'd hope it's sorted by now, in 3 months he's going to have lost a lot of hot water if it isn't!

Plumbers mate, 3 months is nothing!