Hoping for help on a problem that has me stumped.
In the last week or so, we have started experiencing a new problem where our hot water runs cold. I think I've ruled out all the obvious things, and we are not talking about the usual combi boiler problems - we don't have a combi and have a cylinder full of hot water!
Briefly, here's our system: typical gas fired condensing boiler, about 10 years old, heating an adjacent vented hot water cylinder. Hot water is tee'd off the vent pipe at the top in the usual way, then goes directly to a booster pump before feeding the rest of the house. Cold water is also boosted by the same pump, separately from the hot. All has worked basically fine for the 7 years we have lived here. Have always had ample amounts of hot water, throughout the house, at 55-60C, until the last week or so.
Current symptoms:
- ensuite bathroom bath won't run hot by itself, but if I turn on the basin tap at the same time to increase total flow, then the bath runs hot! Same is true of the ensuite shower. Note the flow rate from bath and shower is always what I would normally expect - it's just lukewarm. Also note the ensuite is one of the furthest rooms from the HW cylinder, and the flow rate through the bath tap has never been very strong.
- Main bathroom: this is the first T off the HW pipe approx 3 feet after the booster pump. The bath HW tap (not a mixer) runs fully hot at max flow, but turn it down below 50% flow and it goes lukewarm! This is even though the booster pump is still running ( I can hear it) and the HW cylinder still has hot water in it. Turn the tap back up to full and the water is fully hot again!!
- Kitchen: hot water here runs fully hot at full flow (non mixer tap) but then after a while goes lukewarm and stays that way. I can still get hot water out of the bathroom tap though, straight afterwards!
Things I have investigated and ruled out:
- The boiler: it's working normally and is heating the cylinder;
- The cylinder: the gauge on the vent pipe (and my hands) say it's at 55-60C, and so are the outlet pipes;
- The pump runs as normal when any tap is turned on, and the flow rates seem normal too.
So, I'm flummoxed. If I have HW in the tank, how can I be getting lukewarm water out of some of the (non-mixer) taps? It's almost as if I have a cold supply connected into the HW system downstream of the booster pump, which is pushing cold into the system when the flow is restricted and there is more back pressure on the pump. But how could that be? And why is it happening now when we haven't changed anything??
Thanks for reading if you have got this far. Any ideas or advice welcome!
In the last week or so, we have started experiencing a new problem where our hot water runs cold. I think I've ruled out all the obvious things, and we are not talking about the usual combi boiler problems - we don't have a combi and have a cylinder full of hot water!
Briefly, here's our system: typical gas fired condensing boiler, about 10 years old, heating an adjacent vented hot water cylinder. Hot water is tee'd off the vent pipe at the top in the usual way, then goes directly to a booster pump before feeding the rest of the house. Cold water is also boosted by the same pump, separately from the hot. All has worked basically fine for the 7 years we have lived here. Have always had ample amounts of hot water, throughout the house, at 55-60C, until the last week or so.
Current symptoms:
- ensuite bathroom bath won't run hot by itself, but if I turn on the basin tap at the same time to increase total flow, then the bath runs hot! Same is true of the ensuite shower. Note the flow rate from bath and shower is always what I would normally expect - it's just lukewarm. Also note the ensuite is one of the furthest rooms from the HW cylinder, and the flow rate through the bath tap has never been very strong.
- Main bathroom: this is the first T off the HW pipe approx 3 feet after the booster pump. The bath HW tap (not a mixer) runs fully hot at max flow, but turn it down below 50% flow and it goes lukewarm! This is even though the booster pump is still running ( I can hear it) and the HW cylinder still has hot water in it. Turn the tap back up to full and the water is fully hot again!!
- Kitchen: hot water here runs fully hot at full flow (non mixer tap) but then after a while goes lukewarm and stays that way. I can still get hot water out of the bathroom tap though, straight afterwards!
Things I have investigated and ruled out:
- The boiler: it's working normally and is heating the cylinder;
- The cylinder: the gauge on the vent pipe (and my hands) say it's at 55-60C, and so are the outlet pipes;
- The pump runs as normal when any tap is turned on, and the flow rates seem normal too.
So, I'm flummoxed. If I have HW in the tank, how can I be getting lukewarm water out of some of the (non-mixer) taps? It's almost as if I have a cold supply connected into the HW system downstream of the booster pump, which is pushing cold into the system when the flow is restricted and there is more back pressure on the pump. But how could that be? And why is it happening now when we haven't changed anything??
Thanks for reading if you have got this far. Any ideas or advice welcome!