I'm not a central heating engineer, but neither my central heating installer nor Vaillant have been able to solve my problem.
I had a Vaillant ECOtec plus 428 open vent condensing boiler fitted in November 07, replacing an ancient Servowarm system. Lots of new valves, pump, room thermostat, timer needed, but old radiators and immersion heater.
Over the winter I noticed the boiler kept switching on for a couple of minutes, then off for a few minutes, then back on again.... and my house was no warmer than with the Servowarm. I got adequate hot water. I wasn't impressed by the amount of gas I used - very similar to the Servowarm.
Now it's summer the central heating is off, and the hot water is not as warm as it was in winter - in fact inadequate for a hot bath, and it seems to take longer to heat up. To get a hot bath I have to switch on the central heating (2 radiators on) for an hour at the same time as the water heating is on.
I have observed the boiler closely. This is with the central heating off. I switch the hot water timer on. The boiler fires up, and runs for a few minutes. The temperature indicated on the boiler display zooms up to 70C, then the boiler flame display goes out. The temperature indication drops pretty quickly. The pump is still running. After about 3 or 4 minutes the boiler reignites, but only runs for less than a minute before being off for another 3-4 minutes, by which time the temperature indicator is down to 40C ish.
If I put the central heating on too, a similar thing happens but the period of boiler running is longer.
My amateur diagnosis is that the anticycling feature is kicking in and the overall effect is that there is only hot water in the heating coil in the hot water tank for about 30 seconds out of every five minutes. Hence the tepid water and taking ages to warm it much at all.
Any advice? What can I do to get proper hot water?
I had a Vaillant ECOtec plus 428 open vent condensing boiler fitted in November 07, replacing an ancient Servowarm system. Lots of new valves, pump, room thermostat, timer needed, but old radiators and immersion heater.
Over the winter I noticed the boiler kept switching on for a couple of minutes, then off for a few minutes, then back on again.... and my house was no warmer than with the Servowarm. I got adequate hot water. I wasn't impressed by the amount of gas I used - very similar to the Servowarm.
Now it's summer the central heating is off, and the hot water is not as warm as it was in winter - in fact inadequate for a hot bath, and it seems to take longer to heat up. To get a hot bath I have to switch on the central heating (2 radiators on) for an hour at the same time as the water heating is on.
I have observed the boiler closely. This is with the central heating off. I switch the hot water timer on. The boiler fires up, and runs for a few minutes. The temperature indicated on the boiler display zooms up to 70C, then the boiler flame display goes out. The temperature indication drops pretty quickly. The pump is still running. After about 3 or 4 minutes the boiler reignites, but only runs for less than a minute before being off for another 3-4 minutes, by which time the temperature indicator is down to 40C ish.
If I put the central heating on too, a similar thing happens but the period of boiler running is longer.
My amateur diagnosis is that the anticycling feature is kicking in and the overall effect is that there is only hot water in the heating coil in the hot water tank for about 30 seconds out of every five minutes. Hence the tepid water and taking ages to warm it much at all.
Any advice? What can I do to get proper hot water?