Worcester Bosch Greenstar 37 CDi high gas consumption

[benwhite]

Thanks for the update.

The problem I'm having is not with the boiler - although I don't think it's range rated correctly.

We recently moved into an old 1930s place with solid walls and not much insulation.

My wife and daughter (only 2) are at home during the day, so the heating is on pretty much all the time.

The rads are also ancient, and so undersized for this draughty old place that we have to keep the heating on 24/7 - if we turn it off at night, the temp drops to 16 and it takes more than a whole day to get it back to 20.

My usage in this cold snap has been 9-10 imperial units per day (approx 300KWh). But as I said we have to keep it on ALL the time. Before we had snow (about 8 degrees outside here), my usage was half this.

We have the DT20RF thermostat and that seems incredibly eager to switch the boiler on and off. As soon as it gets to temp it switches it off, and at times it switches the boiler on for 5 min and then off again, only to do the same 15min later!

So, rather than having the same issues as you, I was interested in whether range rating it made a significant difference, simply because my boiler seems to be clicking on and off all the time either due to cycling because the rads are undersized for the boiler or because the thermostat seems to lack any hysteresis.

Anyway. I have new rads waiting to be fitted and a new DT10RF being delivered next week. Hopefully when they're installed the place will heat up quicker which means we should be able to give the boiler a rest while we're in bed!

And then looking at external insulation once this green deal thingy kicks off.

Good luck with it! Be interested if you have a breakthrough. I'll be taking a look at range rating it again once the new rads are in, although may not be necessary since we're going from about 10kw of rads up to 20ish.

 

[jmads]

Bit of a long shot as this thread is 11 years old - but wondering if the original post got this sorted? as my 27 cdi is doing the exact same thing and costing me a fortune! Have tried range rating but that doesnt appear to stop the cycling

 

[jmads]

Hi guys,

Have recently had a new central heating system fitted to an old property I bought. The new system has approx 13kw of radiators at 80 deg flow, Danfoss TRVs and lockshields, and the existing Worcester Bosch Greenstar 37 CDi condensing combi boiler has been re-used as it is only 3 years old and still under warranty.

The system has been piped in two zones, upstairs and downstairs, with a Danfoss 2 port motorised zone valve on each branch in the ground floor boiler cupboard. The zone valves operate as part of a Danfoss wireless system, using a standard wiring centre, an RX2 wireless receiver, with a TP7000RF wireless programmable room thermostat in each zone.

I have just had my first gas bill since installation, and this was double what I expected. I have come to this conclusion as:

1) the weather has been very mild for the billed period
2) our house is south facing with a high amount of double glazing so gets a lot of solar gain with a natural unheated temp of about 13/14 degrees
3) we are out at work five days a week and have a low frost protection setpoint only
4) our programmer settings in each zone are very frugal on temp and on durations of operation i.e. boiler generally only operates in evening and at 20 degrees
5) a few radiators are turned down or off on TRV as room is not currently used,
6) we have been away on holiday for a couple of weeks with frost protection setting left on
7) we also have a wood burning stove which we run at least 2 nights a week which shuts the CH off in the ground floor zone

I observed the boiler operating recently, and noted that when the room stat is calling for heat as zone setpoint is not yet satisfied, the boiler will kick out 80 degree heat then suddenly the ignition indicator light will go out and the flow temp on the control panel will drop to approx 50 degrees. The boiler then seems to idle for a few mins then kicks back in to generate 80 degree heat before repeating the shut off process. I noted from the Danfoss RX2 receiver that the red light which indicates operation of the boiler is required is still lit and calling for heat, so it doesn't appear to be this which is causing the boiler to shut off. I just wondered whether this cycling/modulating should be expected as normal behaviour as I suspect this may be what has caused my high bill?

Thanks for any help!Bit of a long shot as this thread is 11 years old - but wondering if the original post got this sorted? as my 27 cdi is doing the exact same thing and costing me a fortune! Have tried range rating but that doesnt appear to stop the cycling

Bit of a long shot as this thread is 11 years old - but wondering if the original post got this sorted? as my 27 cdi is doing the exact same thing and costing me a fortune! Have tried range rating but that doesnt appear to stop the cycling