Gas usage quadrupled?

dharm999

So, plumber and had a look, a valve is not working which has meant the boiler, is constantly heating water even with the hot water switched off at the controller.  That also explains why the water has been really hot, as the boiler thermostat doesn’t affect the water temperature.  Being fixed next week, so hopefully that sorts out the high gas usage.

Qyburn

That makes sense. On a lot of these systems the boiler/pump is actually switched on by a microswitch on the valve, closed (On) when the valve is open. So if the valve is stuck open it will keep the boiler/pump running irrespective of controller or thermostat.

FreeBear

dharm999 said:

So, plumber and had a look, a valve is not working which has meant the boiler, is constantly heating water even with the hot water switched off at the controller.  That also explains why the water has been really hot, as the boiler thermostat doesn’t affect the water temperature.  Being fixed next week, so hopefully that sorts out the high gas usage.

Got a thermostat on the hot water tank ?

If not, get one fitted when your plumber replaces the valve.

dharm999

So, valve replaced, and thermostat wired in to the hot water tank - there was one on it, just not wired in!  Anyway, outcome is that gas usage has dropped off to 0.75m3 a day, which still looks a bit high, but better than 1.5 or 6m3.  Knock on impact may be that we have to have the hot water on for more than a couple of hours a day, as previously the faulty valve meant it was always heating up, and we never had to worry about running out of hot water, but we’ll see, and adjust it if we need to.  Thanks to all that commented.

FreeBear

dharm999 said:

So, valve replaced, and thermostat wired in to the hot water tank - there was one on it, just not wired in!  Anyway, outcome is that gas usage has dropped off to 0.75m3 a day, which still looks a bit high, but better than 1.5 or 6m3.

Turn the thermostat down to 50-55°C, and that should help to reduce gas consumption. Small changes in usage will help further. e.g. Cold water to wash hands & rinse plates. Shorter showers & less water when filling the bath.

dharm999

Built in thermostat on the Megaflo has a dial that goes from 1 to 5, and the boiler is a dial from 1 to 6, so it’ll be a matter of trial and error to get to the right temperature.  Boiler set to 5 and Megaflo to 4, and will adjust as needs be.

The Megaflo thermostat was not wired in to the valve, so it wasn’t actually doing anything at all, but is now wired in, so all good.

Scot_39

0.75 is c8kWh a day.

Only enough in pure physics of heat exchange to say lift a small tank c 100-120l say from 10 to 60C nominal plus losses. Even the tank heat loop will loose to air on an indirect gas boiler systrm - and it wont be 100% efficient.  Just the tank loss maybe 1kWh small (100+l)  2 kWh large (240-300l) for best modern insulated.

It seems if anything small for such a large property ovef 3 floors and with 4 ? Bathrooms.

And remember its not just the water you use but the hot water remaining in pipework your heating.

So even a quick rinse can add litres to hot water drawn from tank by time flowing really hot at tap.

dharm999

As you say, it may well not be enough, we’ll leave things as they are for now and increase the amount of time, and gas usage, if it needs to be upped. I suspect it will do

dharm999

A quick update.  Gas usage settled down at around 1m3 a day, had to increase the time the hot water was on for, as two hours wasn’t quite enough.  Room that the boiler and tank are in is much cooler now, which is great in the summer but not so good when we get to the colder weather as we left the door to the room open and the heat would heat up the rooms at the back of the house without having to switch the heating on.  But i am assuming that things will balance out, with the heating being on for longer to compensate for the hot water no longer being constantly heated.

QrizB

dharm999 said:

But i am assuming that things will balance out, with the heating being on for longer to compensate for the hot water no longer being constantly heated.

It should do; plus you'll make a saving from not heating the back room for the half of the year where it isn't needed.

Thanks for reporting back!