Gas usage

[ma701ss]

My 3rd post in a few days but gone a bit energy consumption crazy. Have just checked the gas meter readings over one (and a bit) day and it was 158kwh, costing £5.53. We have had the boiler on all day from 9am until 11pm for central heating, and hot water on but the hot water for the boiler should switch off I believe once the cylinder reaches 60 degrees. Is this normal for a condensing boiler? Sounds a lot for one day. We haven't had the fire on, but have used the hob to cook a few meals.

ma701ss

 

[migoplumber]

depends on your boiler effiecency, nowdays there 97% older boilers will be 75% as an idea. also depends on the size of your house, and its thermal effiecency. buckingham palace costs more to heat with its k ratings than a new build 2 bedroom terrace.
im in a semi, gas bill is 100 per month in winter, badly insulated, good boiler

 

[doitmyself]

Have just checked the gas meter readings over one (and a bit) day and it was 158kwh, costing £5.53. We have had the boiler on all day from 9am until 11pm for central heating, and hot water on but the hot water for the boiler should switch off I believe once the cylinder reaches 60 degrees. Is this normal for a condensing boiler? Sounds a lot for one day. We haven't had the fire on, but have used the hob to cook a few meals.

From reading your other posts you have a BG330 boiler aka Glowworm Flexicom hx 31kW. Assuming the 158kW covers just one day of 14 hours (9am-11pm) that means you are only running at an average 158/14 =11.3kW output. Considering the very cold weather at the moment that is very good. Put another way 158kWh is equivalent to running your boiler flat out for 158/31 = 5 hours.

 

[plumbinguser]

I have the downstairs zone on 07:00-22:00 at 20 degrees and upstairs on 00:00-07:00 at 16 degrees, 09:00-16:00 off, 16:00-22:00 at 18 degrees and 22:00-23:59 at 16 degrees, the hot water is set to heat the cylinder for two hour to get to approx 60 degrees. It is a detached house and daily readings are around £4.70 per day but some have been up to £5.50 (approx 190KWh average if calcs based on Eon are correct).

I presume when the cold snap finishes it will come down a bit (I hope so anyway)

 

[ma701ss]

I have had the hot water switched off for about 14 hours now and it still comes out fairly hot from the taps. The pipe going into the cylinder at the bottom is hot and so is the pipe coming out the top. This was before I had turned on any taps so does this sound normal? I wonder if the 3 port valve is letting by still even though it's been renewed.

 

[doitmyself]

I have had the hot water switched off for about 14 hours now and it still comes out fairly hot from the taps. The pipe going into the cylinder at the bottom is hot and so is the pipe coming out the top. This was before I had turned on any taps so does this sound normal? I wonder if the 3 port valve is letting by still even though it's been renewed.

The 3 port valve is usually connected to the cylinder about halfway up. When you say "the pipe coming out of the top", do you mean the very top, ie. the centre of the dome? If so, this is the hot water feed to the taps (the one going up into the loft is the safety vent).

There is a lever in a slot on the side of the valve, which should be at the Auto end of the slot. Move the lever to the other end. You should feel some resistance as you are opening the valve against a spring. If there is no resistance (lever loose) the valve may be sticking. Turn off the electricity to the system (turning programmer HW and CH to OFF is not sufficient) and check the lever again; sometimes this cures the problem. If not remove the actuator (metal box on top of valve) and check that the spindle sticking out of the valve can be turned easily (may only move a quarter of a turn). If it is stiff, apply a little WD40 or similar. Replace actuator and try again.

 

[ma701ss]

Yes the pipe coming out the very top vertically. The 3 port valve is a week old as it was changed when the old one had apparently permanently stuck. At first it seemed to be working, with the pipework into and out of the cylinder turning cold when the hot water was turned off at the programmer, however now the pipework stays hot even when it's turned off. That led me to check the 3 port valve, taking off the motor, and it turns but only turns about a quarter turn as you say, clunking when turned left or right each time. There doesn't seem to be a middle position when I turn it. I checked the position when CH only was on and it was at 45 degrees, I then put it on hot water only and it turned to 90 degrees. I put both on and it went to the 45 degree position again, so I guess it should have been at some other position if both were on? That might explain why the cylinder heats up when only CH is on. I don't understand that though because the valve is only a week old and the motor is obviously turning.

 

[doitmyself]

Yes the pipe coming out the very top vertically.

There will be a Tee piece connected to the top of the cylinder. The pipe going up in to the loft is the safety vent; the one going off at right angles is the hot feed to the taps. These pipes will be hot.

The 3 port valve is a week old as it was changed when the old one had apparently permanently stuck. At first it seemed to be working, with the pipework into and out of the cylinder turning cold when the hot water was turned off at the programmer, however now the pipework stays hot even when it's turned off.

So changing the valve did not really solve the problem.🙁

That led me to check the 3 port valve, taking off the motor, and it turns but only turns about a quarter turn as you say, clunking when turned left or right each time. There doesn't seem to be a middle position when I turn it.

There isn't a physically locatable position. The valve is held half way between the two end positions by the crafty circuit within the actuator.

From what you say, the valve is not sticking so, as the valve is new and unlikely to be faulty, it comes down to a wiring problem.

I checked the position when CH only was on and it was at 45 degrees, I then put it on hot water only and it turned to 90 degrees. I put both on and it went to the 45 degree position again, so I guess it should have been at some other position if both were on?

How were you able to check this with the actuator in position?

Do you have a multimeter? If so, here are some checks you can do.

Turn main supply to system off
Turn room and cylinder stat right down
Set HW and CH OFF at timer
Check valve lever has resistance when moved from Auto to Man.
Remove lid of wiring centre/junction box and locate grey, white and orange wires from the valve.
Turn power ON, turn HW ON at timer.
Turn HW stat to max
Boiler should light and pipe from valve to cylinder get hot. The pipe to rads should not get hot.
Use meter to check voltage on grey wire is 0V and on white wire is 0v
Turn CH ON at timer and turn HW stat up.
Boiler should run and both pipes from the valve get hot
Use meter to check that grey wire has 0v and white wire has 230V
Turn cylinder stat right down
Boiler should run and pipe to rads get hot. Pipe to cylinder should not get hot.
Use meter to check that grey wire has 230v and white wire has 230v
Turn HW OFF at timer
Boiler should run and pipe to rads get hot. Pipe to cylinder should not get hot.
Use meter to check that grey wire has 230v and white wire has 230v.

Please post results of tests, even if you do not have a meter.

 

[ma701ss]

thanks, will test in the next few days. I do have a spare, brand new actuator by the way. Perhaps I should change it? I'm sure it has been working OK, but seems to be a bit temperamental. If the wiring was wrong, surely it would not have worked correctly at all at any point before?

 

[doitmyself]

Don't change the actuator at the moment. Run the tests, even if you do not have a meter, and report the results. This should pinpoint the fault.