Given the sometimes "vigorous" debate on the merits or otherwise of thermal stores and heat banks, I thought people might be interested in my findings on standing losses. Given the debate I was curious ...
OK, I took great care to maximise insulation and minimise losses when I put my store in - but when I tested it on electric only heating I found the losses to be about 80W. My test method was to turn the boiler off and close the valve to prevent external flow round the boiler and CH loops, turn on the immersion heater, and leave for a couple of days to stabilise. I noted the electricity meter reading at the start, after a couple of days, and after another couple of days.
Unsurprisingly, it took a fair bit of energy at first to get the store to a stable condition controlled by the immersion heater stat. Then over the next couple of days it took about 80W average to keep it like that.
During winter (back in Dec/Jan when it was more than a tad parky), I also worked out (by a similar electric only method) that the heating load for the flat is around 2kW. So the 80W standing losses amount to about 4% of the heat load in winter.
For comparison, the house has a BG RD532 combi. From cold this can take up to a minute before hot water comes out of the boiler - it does seem to take an extraordinary time to fire up and ramp up the burner. I do mean a minute to get hot water out of the boiler (I timed it one day) - transit time to the taps is extra. That is with the "ECO mode" turned on.
To deal with this problem, it has a normal mode where it fires up periodically to heat up the main HE and DHW PHE. So over a couple of days I monitored gas usage with CH turned off and nothing else using gas. The gas consumption worked out to about 160W according to the conversion factor on the back of the bill. Given that's it's a significantly bigger property, this is likely to be a smaller percentage of the heating load - but that's not comparing like for like and just shows that you can show almost anything by picking the right numbers
There is a conversion efficiency of one or other boiler* to take into account, but by my measurements, my store has significantly lower standing losses than the combi unless you enjoy waiting for hot water.
IMO neither are particularly significant significant, and the heat losses contribute to the heating input to the property - but I did think it might be a useful data point.
* And before anyone points it out, yes the store is currently fed by an old non-condensing boiler with a pilot light. That's on my list of things to deal with when time and funds permit.
OK, I took great care to maximise insulation and minimise losses when I put my store in - but when I tested it on electric only heating I found the losses to be about 80W. My test method was to turn the boiler off and close the valve to prevent external flow round the boiler and CH loops, turn on the immersion heater, and leave for a couple of days to stabilise. I noted the electricity meter reading at the start, after a couple of days, and after another couple of days.
Unsurprisingly, it took a fair bit of energy at first to get the store to a stable condition controlled by the immersion heater stat. Then over the next couple of days it took about 80W average to keep it like that.
During winter (back in Dec/Jan when it was more than a tad parky), I also worked out (by a similar electric only method) that the heating load for the flat is around 2kW. So the 80W standing losses amount to about 4% of the heat load in winter.
For comparison, the house has a BG RD532 combi. From cold this can take up to a minute before hot water comes out of the boiler - it does seem to take an extraordinary time to fire up and ramp up the burner. I do mean a minute to get hot water out of the boiler (I timed it one day) - transit time to the taps is extra. That is with the "ECO mode" turned on.
To deal with this problem, it has a normal mode where it fires up periodically to heat up the main HE and DHW PHE. So over a couple of days I monitored gas usage with CH turned off and nothing else using gas. The gas consumption worked out to about 160W according to the conversion factor on the back of the bill. Given that's it's a significantly bigger property, this is likely to be a smaller percentage of the heating load - but that's not comparing like for like and just shows that you can show almost anything by picking the right numbers
There is a conversion efficiency of one or other boiler* to take into account, but by my measurements, my store has significantly lower standing losses than the combi unless you enjoy waiting for hot water.
IMO neither are particularly significant significant, and the heat losses contribute to the heating input to the property - but I did think it might be a useful data point.
* And before anyone points it out, yes the store is currently fed by an old non-condensing boiler with a pilot light. That's on my list of things to deal with when time and funds permit.
