24-11-2016, 10:20 AM
Living in the sticks, we are off the grid for gas, the closest that the gas pipes get is the two two miles away. So, we are on oil heating rather than gas or storage heating.
Main boiler is a Grant combi 90, the type fitted with a cast iron burner chamber and a Riello burner unit. Reasonably reliable, the only fixes I had to do over the last nine years or so was a replacement expansion cylinder as the old one had rotted internally.
However, and a big however at that, all things wear, and we were aware that one of the thermostats was getting a bit sticky in operation, causing the burner to stick on rather than cycle and raising the temp until the overhead tripped. This usually happened during having a shower, a good warning that you was spending too long in there watering your bits. I noticed during an inspection that the heat exchanger was looking distressed, this due to a previous owner bodging a repair and using instant gasket on a connecting joint rather than the proper fibre washer. So, duely armed, I spent £200 on all new thermostats and an exchanger, and spent a morning changing out the parts.
Worst of British design kicks in. The adjuster for one of the stats is hidden within the casing, so five minutes with a power drill produced a port to stick an adjustment screwdriver, allowing me to set up the call down stat without wiring myself to the national grid.
If anybody has to set up such a boiler after a repair, or somebodies little johnny has had a tweak, it's reasonably simple provided you have a meter with a thermocouple probe. In my case, put the probe in the top stat pocket and adjust the main thermostat until it turns the Riello burner off at 82 degrees, then mark the position with a small dob of white paint for future reference in case little johnny comes around. Next, put the probe in the bottom stat pocket and adjust the call down stat to 75 degrees and that should be it. Turn on hot water, temp in reserve drops below 75, bottom stat turns on boiler. Heat creeps above 82 and top stat turns it off. Boiler will cycle between these two temps on demand during either heating or hot water. On shutdown, temp in reserve will climb to around 100 on residual heat but will go nowhere the 111/112 on the overtemp trip unless there is gunge in the system which causes all sorts of other grief.
Main boiler is a Grant combi 90, the type fitted with a cast iron burner chamber and a Riello burner unit. Reasonably reliable, the only fixes I had to do over the last nine years or so was a replacement expansion cylinder as the old one had rotted internally.
However, and a big however at that, all things wear, and we were aware that one of the thermostats was getting a bit sticky in operation, causing the burner to stick on rather than cycle and raising the temp until the overhead tripped. This usually happened during having a shower, a good warning that you was spending too long in there watering your bits. I noticed during an inspection that the heat exchanger was looking distressed, this due to a previous owner bodging a repair and using instant gasket on a connecting joint rather than the proper fibre washer. So, duely armed, I spent £200 on all new thermostats and an exchanger, and spent a morning changing out the parts.
Worst of British design kicks in. The adjuster for one of the stats is hidden within the casing, so five minutes with a power drill produced a port to stick an adjustment screwdriver, allowing me to set up the call down stat without wiring myself to the national grid.
If anybody has to set up such a boiler after a repair, or somebodies little johnny has had a tweak, it's reasonably simple provided you have a meter with a thermocouple probe. In my case, put the probe in the top stat pocket and adjust the main thermostat until it turns the Riello burner off at 82 degrees, then mark the position with a small dob of white paint for future reference in case little johnny comes around. Next, put the probe in the bottom stat pocket and adjust the call down stat to 75 degrees and that should be it. Turn on hot water, temp in reserve drops below 75, bottom stat turns on boiler. Heat creeps above 82 and top stat turns it off. Boiler will cycle between these two temps on demand during either heating or hot water. On shutdown, temp in reserve will climb to around 100 on residual heat but will go nowhere the 111/112 on the overtemp trip unless there is gunge in the system which causes all sorts of other grief.
