DHW heat exchanger changed. No difference.
vaillant tepid hot water
- Thread starter Smithysmith
- Start date
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No surprise really.
Unless you can find someone competent (and none of them have a clue so far) there's little further advice to give. It doesn't get much simpler than measuring burner pressures and gas rates.
Forget the servo and diverter...you've already said the flow pipe doesn't heat up with the hot water on.
Unless you can find someone competent (and none of them have a clue so far) there's little further advice to give. It doesn't get much simpler than measuring burner pressures and gas rates.
Forget the servo and diverter...you've already said the flow pipe doesn't heat up with the hot water on.
Thanks
I've tried to get through to Vaillant again today with no success. There was a slight leak on the heat exchanger so I thought it was worth the effort changing it as I managed to get a new one (and new type) for £50. The reason I was going for the diverter and servo is that the last corgi thought it might not be opening fully and this may be caused by worn springs in either or both the valves. I'll take your advice and get the pressures checked again before buying the valves. The standing gas pressure is 28 mbar. Theres a Scottish gas engineer stays down the road from me, I'll ask him if he'll check the pressures. I'm still a bit baffled by the fact that I'm only burning half the gas I should. Would a new gas valve be the answer if there's a problem with the pressure?
I've tried to get through to Vaillant again today with no success. There was a slight leak on the heat exchanger so I thought it was worth the effort changing it as I managed to get a new one (and new type) for £50. The reason I was going for the diverter and servo is that the last corgi thought it might not be opening fully and this may be caused by worn springs in either or both the valves. I'll take your advice and get the pressures checked again before buying the valves. The standing gas pressure is 28 mbar. Theres a Scottish gas engineer stays down the road from me, I'll ask him if he'll check the pressures. I'm still a bit baffled by the fact that I'm only burning half the gas I should. Would a new gas valve be the answer if there's a problem with the pressure?
you have just answered yer own question 1/2 the gas 1/2 the heat input
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i dont think he was actually checking the burner pressure. In fact I've no idea what he was checking, never had areading when turned off (and shut off). except slight fan induced reading which is only a small blip on the gauge.
Hopefully this is the information you are looking for.
Pressure at meter is 28mbar
pressure at meter with hot water running full is 23mbar
pressure at meter with central heating on is 23 mbar
pressure at check point on boiler is 7.5 mbar when CH or DHW in use.
I can confirm that it's not the DHW heat exchanger and it's not the divertor valve. All the pipework from the servo to the valve have also been checked and deemed clear.
Forgive my stupidity but does the meter readings indicate that the boiler is running at 5mbar (I'm subtracting the 23 from 28 here)? Or is the boiler running at 2mbar too high given that the working pressure is factory set at 5.1mbar?
Pressure at meter is 28mbar
pressure at meter with hot water running full is 23mbar
pressure at meter with central heating on is 23 mbar
pressure at check point on boiler is 7.5 mbar when CH or DHW in use.
I can confirm that it's not the DHW heat exchanger and it's not the divertor valve. All the pipework from the servo to the valve have also been checked and deemed clear.
Forgive my stupidity but does the meter readings indicate that the boiler is running at 5mbar (I'm subtracting the 23 from 28 here)? Or is the boiler running at 2mbar too high given that the working pressure is factory set at 5.1mbar?
(it's not the servo either)
Just a thought, given that my gas usage is over all higher yet my flow rate per minute is half of what it should be when drawing how water, could it be that the burner injectors are choked and therefor restricting the flow of gas? Could the working pressure at the boiler be higher as a result of the flow being restricted? Another thought, could it be the fan is running out of steam and not drawing the emissions away fast enough and therefor the boiler wont allow more gas in?
I'm only asking because you all seem to be pretty much experts.
Also. At my ground floor kitchen tap (15mm fed) I can now run 5 l/min at 50 degrees pretty constant, Anything above 7 l/min and it's back to tepid. At my first floor w/h/b (15mm fed) I get similar results but with a lower flow and at my first floor bath tap (22mm fed) it runs hot at a very low flow rate then the boiler usually fires down and the water trickles stone cold.
Is everyone bored with me now?
Just a thought, given that my gas usage is over all higher yet my flow rate per minute is half of what it should be when drawing how water, could it be that the burner injectors are choked and therefor restricting the flow of gas? Could the working pressure at the boiler be higher as a result of the flow being restricted? Another thought, could it be the fan is running out of steam and not drawing the emissions away fast enough and therefor the boiler wont allow more gas in?
I'm only asking because you all seem to be pretty much experts.
Also. At my ground floor kitchen tap (15mm fed) I can now run 5 l/min at 50 degrees pretty constant, Anything above 7 l/min and it's back to tepid. At my first floor w/h/b (15mm fed) I get similar results but with a lower flow and at my first floor bath tap (22mm fed) it runs hot at a very low flow rate then the boiler usually fires down and the water trickles stone cold.
Is everyone bored with me now?
A big thank you to all who have given me the benefit of your expertise. I now have roasting hot water throughout the house.
I changed my DHW heat exchanger which was leaking a bit anyway Cost £65 (brand new from ebay). I changed the servo and the divertor valve (£35 for the servo (plumb centre) and £44 for the divertor brand new from ebay) as it had been suggested that these were common ailments to these boilers. THOSE WHO HAVE READ THE COMPLETE SAGA WILL KNOW THAT 'GASGURU' TOLD ME FROM THE START IT WASN'T THE SERVO OR THE DIVERTOR OR THE HEAT EXCHANGER. Many thanks to you Gasguru your persistence with the problem being with the gas drove me in a diffirent direction.
The out come:
I took out the injectors and burner (they looked like new and remember this boiler has been regularly serviced) I brushed them and hoovered them but they seemed ok, I cleared the injector nozzles though they seemed pretty clear and finally I took my air compressor and blew compressed air into the burner and hey presto a hold load of dust came out (full mask and disposable overall on of course), put it all back together and now I've hot water the way it should be. Poor servicing? Uncommon fault? Stupid me for not having the sense to suspect the burner?(remember it looked clear and operated well enough to convince 3 corgi plumbers there wasn't a problem with the gas. Who knows, but it's fixed.
Total cost £164 (I bought a manometer to check gas pressure £20) Could have got away wit not paying anything had I known but still a cheap fix. I'm keeping the new parts I installed as I see no point in taking them out to resell.
Many thanks again.
Smithysmith
I changed my DHW heat exchanger which was leaking a bit anyway Cost £65 (brand new from ebay). I changed the servo and the divertor valve (£35 for the servo (plumb centre) and £44 for the divertor brand new from ebay) as it had been suggested that these were common ailments to these boilers. THOSE WHO HAVE READ THE COMPLETE SAGA WILL KNOW THAT 'GASGURU' TOLD ME FROM THE START IT WASN'T THE SERVO OR THE DIVERTOR OR THE HEAT EXCHANGER. Many thanks to you Gasguru your persistence with the problem being with the gas drove me in a diffirent direction.
The out come:
I took out the injectors and burner (they looked like new and remember this boiler has been regularly serviced) I brushed them and hoovered them but they seemed ok, I cleared the injector nozzles though they seemed pretty clear and finally I took my air compressor and blew compressed air into the burner and hey presto a hold load of dust came out (full mask and disposable overall on of course), put it all back together and now I've hot water the way it should be. Poor servicing? Uncommon fault? Stupid me for not having the sense to suspect the burner?(remember it looked clear and operated well enough to convince 3 corgi plumbers there wasn't a problem with the gas. Who knows, but it's fixed.
Total cost £164 (I bought a manometer to check gas pressure £20) Could have got away wit not paying anything had I known but still a cheap fix. I'm keeping the new parts I installed as I see no point in taking them out to resell.
Many thanks again.
Smithysmith
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