Ideal C35 Running Cost

[CraigieUK]

Evening - looking for some comparative info in relation to the C35 installed at our home. We have the heating set at 21c from around 8am to 10pm, and off at other times. The heating turns on and off throughout the course of the day as the temperature is reached. According to our OVO account we are using in excess of 400kwh of gas per day which seems excessive when the output is only 24kw. We live in a regular 3 bed bungalow and have no other gas appliances. Does anyone have any comparative data or clever enough to work out whether these numbers look correct. Thanks!

 

[muggles]

Excessive is one way of putting it, damn near impossible is another. To use 400kwh/day your boiler would need to be firing at full power for almost 17 hours per day

 

[CraigieUK]

Yeah, that's what we thought!

 

[Old Salt]

I have used 408 kwh this week from Midnight on Sunday (9th) to midnight on Sunday (16th). 2 bed bungalow heating and water ideal logic boiler.

 

[MNW67]

Evening - looking for some comparative info in relation to the C35 installed at our home. We have the heating set at 21c from around 8am to 10pm, and off at other times. The heating turns on and off throughout the course of the day as the temperature is reached. According to our OVO account we are using in excess of 400kwh of gas per day which seems excessive when the output is only 24kw. We live in a regular 3 bed bungalow and have no other gas appliances. Does anyone have any comparative data or clever enough to work out whether these numbers look correct. Thanks!

Do you get half hourly usage breakdown in your OVO online account?

What has the outside temperature been during this period of usage?

 

[CraigieUK]

Thanks for asking. I can only see a daily usage on the OVO app, and outside temperature has been around 3c (for what seems like forever!).

 

[CraigieUK]

I have used 408 kwh this week from Midnight on Sunday (9th) to midnight on Sunday (16th). 2 bed bungalow heating and water ideal logic boiler.

May I ask what model you have and what it's max output is? Ours is a C35 and from what I have found online the max output is 24kw.

 

[MNW67]

Thanks for asking. I can only see a daily usage on the OVO app, and outside temperature has been around 3c (for what seems like forever!).

I am also with OVO.

You can ask them to show half hour usage from now on. That might give more useful information.

 

[DP]

May I ask what model you have and what it's max output is? Ours is a C35 and from what I have found online the max output is 24kw.

C35 is a 35 kW combi boiler. When running a hot tap, it will fire at 35 kW and then modulate to maintain temperature.

For heating multiply each radiator by 1.5 to guesstimate the load on the boiler- doubt it will come to 18kW even.
Do you have a room thermostat or relying on TRVs to regulate heat. TRVs do not control the boiler
Consider smart TRVs to take control of all the rads and boiler thus reducing the fuel useage.

 

[Old Salt]

May I ask what model you have and what it's max output is? Ours is a C35 and from what I have found online the max output is 24kw.

Mine is a C30 max output still 24kw

 

[fixitflav]

C35 is a 35 kW combi boiler.

35 kW is about 38 kW input, so if it's on flat out could be 10 hours/day. Still seems excessive, but maybe OP lives in a mansion.

There was a recent thread on same subject. Not sure how it panned out but might be useful. https://www.diynot.com/diy/threads/...not-sure-what-to-try-next.641212/post-5908505

 

[CraigieUK]

35 kW is about 38 kW input, so if it's on flat out could be 10 hours/day. Still seems excessive, but maybe OP lives in a mansion.

There was a recent thread on same subject. Not sure how it panned oput but might be useful. https://www.diynot.com/diy/threads/...not-sure-what-to-try-next.641212/post-5908505

Haha...sadly not. Just a very modest 3 bed bungalow.

 

[fixitflav]

Haha...sadly not. Just a very modest 3 bed bungalow.

Mmm 400 kWh does seem a lot then

 

[CraigieUK]

I've trawled through various forums this morning and think I may have stumbled on something. Could it be possible that OVO are billing me based on an imperial calculation instead of metric? I knocked up a quick excel and ran the daily m3 readings thru since we moved in back in July '24. The meter is metric (m3). Findings were really interesting. When I convert readings to imperial, the kWh comes out very, very close to those being reported by OVO. What do you think? I'll post a link to the sheet if anyone wants to see / use it.

 

[Harry Bloomfield]

I've trawled through various forums this morning and think I may have stumbled on something. Could it be possible that OVO are billing me based on an imperial calculation instead of metric? I knocked up a quick excel and ran the daily m3 readings thru since we moved in back in July '24. The meter is metric (m3). Findings were really interesting. When I convert readings to imperial, the kWh comes out very, very close to those being reported by OVO. What do you think? I'll post a link to the sheet if anyone wants to see / use it.

Check your meter, it will show you which, take a photo of it, then check what your bill says about M3, or Imperial - if they do not agree, email Ovo the photo.