Hi,
I’m new to the forum but thought I’d sign up to try and get some help with a customers boiler.
Bit of background on the boiler first. The house was renovated extensively with new bathrooms kitchen etc and the above boiler fitted 4 1/2 years ago approx, with no other work done inside or to the boiler since as far as I’ve been told.
I have recently become their regular plumber with anothe of their projects so am now looking after their boiler.
Beginning of March I got a text asking for boiler to be serviced because the hot water wasn’t lasting more than a minute.
Gave boiler a full service still poor hot water, so went through the MI fault finding as not to miss anything and drew a blank other than faulty heat exchanger.
I have had another installer with me on the job and have spoken to grant technical twice now and a grant rep twice who still can’t think of a solution.
When you turn on a hot tap the flow, demand and DHW pump light activate yet the boiler doesn’t fire even after 4+ mins. The flow of primary water into exchanger is too hot to touch yet the return out back to boiler starts too hot then goes cold as does the DHW pipe from exchanger to blending valve. If you turn the tap off the primary return heats back up to match the flow into the exchanger (have measured with thermometer). The store will heat up and become satisfied leaving only the power led lit. CH works fine.
So far myself and the other installer have done the following work. New heat exchanger, as advised by grant technical, check valve fitted on DHW pipe to property again as advised by Grant technical, both thermistors tested and changed, CH and DHW pumps swapped over to eliminate pump problem, return manifold pipe taken off to check for blockage, PCB taken from my own grant boiler and tried as to avoid cost of a new one, new blending valve fitted (guess at the possibility of a fault forcing cold back into the heat exchanger backwards)
Going out of my mind trying to fathom
It out and with the grant engineer for our area on leave for another week no hope of anyone other than another installer coming to have a look.
It could be something stupidly simple I’m missing or haven’t tried but with two of us now having worked at it we’re both stumped along with another guy I rang after grant giving me his number as he does warranty work for them.
Can anyone help me please as to what it could be or what I could check? It’s almost as if the flow rates through the taps are too high but the MI states 18lpm max and I’ve had readings from three taps one at 10 one at 8 and one around 5 because iso valve is closed down. Mains pressure has been tested at 4.5 bar ish and being in north cornwall we have soft water so don’t suffer from limescale.
I’m relatively new to the oil industry and have already decided I don’t like grants from my experiences with them.
Sorry for the essay but wanted to explain as much as I could to avoid answering the same questions.
Thanks
Nathan
I’m new to the forum but thought I’d sign up to try and get some help with a customers boiler.
Bit of background on the boiler first. The house was renovated extensively with new bathrooms kitchen etc and the above boiler fitted 4 1/2 years ago approx, with no other work done inside or to the boiler since as far as I’ve been told.
I have recently become their regular plumber with anothe of their projects so am now looking after their boiler.
Beginning of March I got a text asking for boiler to be serviced because the hot water wasn’t lasting more than a minute.
Gave boiler a full service still poor hot water, so went through the MI fault finding as not to miss anything and drew a blank other than faulty heat exchanger.
I have had another installer with me on the job and have spoken to grant technical twice now and a grant rep twice who still can’t think of a solution.
When you turn on a hot tap the flow, demand and DHW pump light activate yet the boiler doesn’t fire even after 4+ mins. The flow of primary water into exchanger is too hot to touch yet the return out back to boiler starts too hot then goes cold as does the DHW pipe from exchanger to blending valve. If you turn the tap off the primary return heats back up to match the flow into the exchanger (have measured with thermometer). The store will heat up and become satisfied leaving only the power led lit. CH works fine.
So far myself and the other installer have done the following work. New heat exchanger, as advised by grant technical, check valve fitted on DHW pipe to property again as advised by Grant technical, both thermistors tested and changed, CH and DHW pumps swapped over to eliminate pump problem, return manifold pipe taken off to check for blockage, PCB taken from my own grant boiler and tried as to avoid cost of a new one, new blending valve fitted (guess at the possibility of a fault forcing cold back into the heat exchanger backwards)
Going out of my mind trying to fathom
It out and with the grant engineer for our area on leave for another week no hope of anyone other than another installer coming to have a look.
It could be something stupidly simple I’m missing or haven’t tried but with two of us now having worked at it we’re both stumped along with another guy I rang after grant giving me his number as he does warranty work for them.
Can anyone help me please as to what it could be or what I could check? It’s almost as if the flow rates through the taps are too high but the MI states 18lpm max and I’ve had readings from three taps one at 10 one at 8 and one around 5 because iso valve is closed down. Mains pressure has been tested at 4.5 bar ish and being in north cornwall we have soft water so don’t suffer from limescale.
I’m relatively new to the oil industry and have already decided I don’t like grants from my experiences with them.
Sorry for the essay but wanted to explain as much as I could to avoid answering the same questions.
Thanks
Nathan
