Can't get any hot water when central heating is not on. Can anyone help?

Pete, February 2008

start with dhw flow switch replace... failing that its the diaphram sticking which is a bigger job and should be left to the pros.

kev duncan, May 2010

bit late with this but it may benefit other alpha users after getting no hot water after turning hot on , i manually pressed the switch and the burner fires up and hot water follows ,,so i dismantled the switch from its saddle and put in a very thin plastic washer between the micro switch and the white plastic plunger ,thus when activated the travel to press the switch is less which can take up wear and tear within the switch/DHW/CH diverter valve ,,so far so good

scruffy, December 2008

I have the same problem and in the next few days I intend to check the flow switch with a view to replacing the diaphram as was suggested to me.

Leon Golding, April 2008

I always turn off gas and then electric before doing anything like this localised problem on my boiler. Same problem as yours. I'm inclined to think the dhw switch itself is the problem as I've had my diverter changed and still same issue. Problem seems to happen in cold temperatures more. I'm thinking that there is some sticking either inside the dhw switch or the dhw switch with its saddle piece is moving slightly. My switch activates hotwater when the connection open i.e. closed means boiler inactive. Don't know if thats normal, but it worked for a day or so unless its position is wrong.

Saif, March 2008

I have same problem intermitantly and I'm trying to work out where the fault is, its definately a sensor problem on mine.

I've pulled down the front panel and there are various flow and temperature sensors. Check the back of the main boiler cover for circuit diagram.

I've reseated some of the connectors for the temp and flow sensors and I am always able to get the hot water working, but after a few days it may stop again.

I have a sink right next to the boiler so its easy to monitor the thing when I turn on the hot tap and listen for the clicking of the solenoids.

So I'm in the process of eliminating which switch is causing the problem, but at the moment I think its the temperature sensor on the hot water (2 green wires).

Either that or a dry joint, I might have the back of the panel off if it stays intermitant.

Good luck.

Lib, February 2008

call a gas man pal

dave, February 2008