Visited a rented property today reporting Hot water fine but no central heating! Gas fire works fine and bbu pilot lights ok. Located imersion tank and top half nice and hot but bottom stone cold - tank has 4 22mm feeds from it. Suspected problem might be pump or zone valve but can't find either. Am sure I can hear the pump somewhere near the fire and suspect it might be under the nice new laminate floor and floor boards. Bbu refuses to go to full flame but will happily sit there on pilot no problems. Stumped me so time to seek advise and guidance from those with more knowledge and experience than myself. Thanks in advance
Baxi Bermuda back boiler HW ok but no CH
- Thread starter keighern
- Start date
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could be pumped ch and gravity hot water going by your description
laminate up, and pump checked for operation is reqd
laminate up, and pump checked for operation is reqd
Cheers for the quick response glasgowgas. If I can hear the pump do I still need to expose to check it? Also would the pump stop the bbu comin upto full flame?oh and one last thing! All but one pipe from the bbu go up to the 1st floor to the tank, the other goes down under the floor. Have checked and def can't find pump or zone valve near the tank on first floor! Thanks again
wee test
switch off ch and dhw at programmer
run all hot taps so cylinder is cold
switch on hot water only. if bbu fires up (it will!) feel coil at cylinder, will be getting nice n warm
switch on ch (or ch and hot water). no heat to rads = duff pump
when cylinder gets to temp no pump running to feed rads, bbu thermostat satisfied, bbu dont fire
cmon fella of course you will have to physically check pump operation, by removing vent screw and checking impellor
switch off ch and dhw at programmer
run all hot taps so cylinder is cold
switch on hot water only. if bbu fires up (it will!) feel coil at cylinder, will be getting nice n warm
switch on ch (or ch and hot water). no heat to rads = duff pump
when cylinder gets to temp no pump running to feed rads, bbu thermostat satisfied, bbu dont fire
cmon fella of course you will have to physically check pump operation, by removing vent screw and checking impellor
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Thanks for your patience glasgowgas. Decided that I'm going back tomorrow to see if I can resolve. Does it sound reasonable that the 1 pipe I cant see much of as it goes down under the floor (the one from the bottom of the BBU) is the one with the pump on? anything else worth checking whilst I'm at it? Will follow your advice and see what happens. With this type of system does the BBU heat both domestic hot water and central heating? As you can tell, I have pretty much no experience of this kind of setup and only tend to work on combis so dont really know how these systems work!! thanks again. Much appreciated
Quite common practice on the older pumped CH/Gravity HW systems to have the pump on the return, just before boiler. Where though is anybodies guess, seen them behind panels, under floors, know of one in an understairs cupboard, opposite side of the house.
Usually the BBU would heat the DHW cylinder through a gravity primary circuit, 28mm flow and return, though later installations became fully pumped.
Usually the BBU would heat the DHW cylinder through a gravity primary circuit, 28mm flow and return, though later installations became fully pumped.
Tried suggestions today Glasgowgas
Located pump - all working OK
Ran off hotwater until tank cold
Turned on demand for hot water via controller
BBU still failed to fire up!
Any ideas? Could it be a component of the multi function gas valve (solenoid?) not sure how to test
Thanks for your patience and advice
Located pump - all working OK
Ran off hotwater until tank cold
Turned on demand for hot water via controller
BBU still failed to fire up!
Any ideas? Could it be a component of the multi function gas valve (solenoid?) not sure how to test
Thanks for your patience and advice
do you own a multimeter, there must be either 2 x 2 port valve or 1 x 3 port valve somewhere on the line, or how else was water hot in the cylinder?
Yep, tried both and BBU still didnt fire up! Checked hot water tank hour or so later after I'd relayed some of the laminate flooring and water was hot again. Could the tank be heating the hot water on its own? Had looked everywhere when looking for the pump and didnt come across any zone valves! The controller has been battered (its a student house and they dont seem to care a toss!) and although the lights work I'm starting to think that its not working properly. Loosing the will to live.....Cheers
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