Very expensive new central heating

Merlin5 · 23 Jan 2013

I live in a small one bedroom ground floor flat which I bought years ago. I had central heating installed about 2 months ago, 4 rads and a heated towel rail and a Vaillant 831. I'm still on a pre-paid meter with british gas but intend to switch to direct debit. Anyway, with only a few hours of heating a day at 21c and only one rad and the heated rail on, I'm seeing £30 go about every 10 days! £90 a month, it's ridiculous. I put another £30 in last night using 3 rads and have used £4 of that already.

British gas told me on the phone yesterday that pre-paid is not more expensive than direct debit anymore, but surely that can't be right because these costs seem unreasonable for just 2 or 3 rads. I'm wondering, I use a wireless Salus RT500RF to control when the heating is on and off but is it possible that the combi boiler is still running my gas down (not including hot water) even while the heating is off by the thermostat controller and should I be turning something off on the boiler itself to conserve more gas?

Dan Robinson · 23 Jan 2013

Pre-paid meters will rape you, then rape you again sideways.

Get off it ASAP. Then take actual meter readings from day one.

ALEC1 · 23 Jan 2013

£3 a day is what it is costing these days to keep you warm...its really nothing...not even a pint of beer... but as Dan says, prepay is more expensive...

picasso · 23 Jan 2013

Is there a "C" shown on the display on the boiler ?

D_Hailsham · 23 Jan 2013

Merlin5 said:
I live in a small one bedroom ground floor flat. ... I had central heating installed ... a Vaillant 831.

The CH output of your boiler is 8.7 - 24kW; HW output is 31kW
The boiler is probably fine for hot water, but it's way over size for your flat.

Use Whole House Boiler Size Calculator to find the heating requirement of your house. (Set HW requirement to 0 instead of 2000 as you have a combi.)

You may well find that the requirement is less than the minimum 8.7kW output of your boiler. This is typical for a combi boiler which has to be sized for the hot water requirement.

Replacing the boiler is obviously out of the question but reducing the maximum output, currently 24kW, will help. Setting it to slightly above the value given by the calculator, or 10kW if the value is below 8.7kW, will help.

You do this by changing the value of the d.0 parameter - see Installation Manual.

algas · 23 Jan 2013

Also I think with a pre pay meter you are paying the standing charge daily,
as well as your gas usage.

Alan

Agile · 23 Jan 2013

We had a lady recently who did not realise that £1400 pa was normal for a four bedroom house!

Your heating costs seem quite normal to me!

Tony

pat50 · 23 Jan 2013

D_Hailsham said:
The CH output of your boiler is 8.7 - 24kW; HW output is 31kW
The boiler is probably fine for hot water, but it's way over size for your flat.

I believe the "new" 831 modulates down to 5.2kw.

D_Hailsham · 23 Jan 2013

pat50 said:
I believe the "new" 831 modulates down to 5.2kw.

That's correct. However the OP's requirement may be even less than that!

ianmcd · 23 Jan 2013

Agile said:
We had a lady recently who did not realise that £1400 pa was normal for a four bedroom house!

Your heating costs seem quite normal to me!

Tony

Tony OP lives in a 1 bedroom flat ! what are you on about ?

Merlin5 · 23 Jan 2013

Thanks for the replies guys.

Dan, yeah, I'm definitely getting off pre paid asap.

Alec, very true. My nephew has duel fuel with southern electric and tells me he pays £59 a month for the gas with more rads on and for longer than me. So I'd be fairly happy with that sort of monthly gas payment.

picasso, yes there's a big C on the display, whatever it means.

D_Hailsham, many thanks for your detailed reply. I'm afraid it's all pretty much over my head though so I rang my installation engineer and told him what you said. I didn't really understand much of what he explained either lol, and while he agreed with your minimum and maximum output numbers for my boiler, I think the jist of what he said was that the modulator is taking care of what I need and that it starts at 24w and quickly adjusts down as it sees fit. Or something like that. He said making adjustments isn't really going to make much difference, isn't really going to save me anything, would affect the overall performance of the boiler, and that the best thing to do is get off the prepayment meter. So I guess I'll just have to use hot water bottles and my electric blanket a bit more during this mini ice age until my meter and tariff is changed.

Btw, I was intending to have a cheaper boiler installed, a Main. My gas installation engineer said he could install it but said it would be crap and might give all sorts of problems, and that it's worth spending a bit more for the Vaillant Ecotec Plus 831, which I did. He got me a 7 year warranty on it too.

picasso · 23 Jan 2013

The big "C" means you have hot water preheat on,(the boiler keeps its self warm ready for instant hot water) have a look in the instructions if you want to turn it off.

Merlin5 · 23 Jan 2013

picasso said:
The big "C" means you have hot water preheat on,(the boiler keeps its self warm ready for instant hot water) have a look in the instructions if you want to turn it off.

Thanks, I'll look in the manual. I took note of the amount of money left showing on the digital readout of my meter this morning, turned the Salus off and when I came home this afternoon, there wasn't any change. So I presume that means that the preheat function isn't draining
gas?

D_Hailsham · 23 Jan 2013

Merlin5 said:
I'm afraid it's all pretty much over my head

I'm sure that using the online calculator should be within your capabilities.

I think the jist of what he said was that the modulator is taking care of what I need and that it starts at 24w and quickly adjusts down as it sees fit.

That's the problem! It starts at max output and then reduces, which does not happen immediately, it takes a time. So the boiler temperature rises very quickly because the radiators cannot get rid of the heat. This causes the boiler to shut down, wait for the water to cool down, and restart. And so the stop/start cycle continues.

He said making adjustments isn't really going to make much difference, isn't really going to save me anything, would affect the overall performance of the boiler,

Reducing the maximum output will improve the performance of the boiler because it will not be turning on and off so often. You are not the first person on this forum with this problem and the advice has always been to reduce the max output of the boiler. This does NOT affect the Hot Water performance of the boiler.

the best thing to do is get off the prepayment meter.

This will reduce your bill compared to a prepayment meter, but it won't reduce the amount of gas consumed.Setting the Max output to a more realistic value will help reduce your consumption.

Agile · 23 Jan 2013

As far as I am aware you no longer pay and or significantly more for a prepayment meter.

You get a standing charge regardless of the type of meter!

Tony

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Very expensive new central heating

ALEC1

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