Victorian mid-terrace central heating

BUFF

1905 Edwardian 3-bed mid-terrace in Glasgow (so Northern) here.
Typically 7,500-8,500kWh p.a. depending upon the year's weather. My gas consumption for January 2022, 1205 kWh.

Heated by a condensing combi running low flow temps (this does mean it can take hours to raise building temp. significantly but that's what a programmer is for) typically to ~16C (set point of 14.5C on the roomstat which is in the coldest room in my house). Standard TRVs on all rads bar 1.
Loft insulated, extensive draught-proofing. Rear of house double-glazed (Conservation Area so can't do front at an economical price), thermal curtains used. I wear an extra layer.

How many baths/showers per week are taken in your house? 
What are your TRVs set to (although hopefully your Nest will prevent anything excessive actually being reached)?

BUFF

MWT said:

 That boiler looks a bit over-sized for a 3 bed property, which will make it harder for it to run efficiently, but there may be reasons for it if your installer did a proper job in determining the output required, or not, if that just happened to be what he had available in stock

If it's a combi it will be for DHW flow rate.

westie2128

Sounds high to me aswell. 

Ours is 9078 kWh per year (for heating and hot water only) - mid terrace, property build in 1840’s - boiler is 6 years old and the heating is on from 5am until 11pm, set at 23 degrees

It takes a few hours in the morning to reach 23 degrees but once it does, the boiler just clicks on/off throughout the day to top it up, rather than it running solid for hours in the morning and again hours in the evening trying to get to temperature when on a timer. 

Barmy_Army_92

Thanks for the responses so far, our EPC recommends cavity insulation to save an estimated 2-3k kWh per year in heating costs. Before any changes, the EPC calculated space and water heating as requiring 17,500 kWh per year. I think with the new boiler and room thermostat we are already on course to dip below that 17.5K, and upgrading loft insulation/cavity wall insulation is getting considered prior to next winter. 

MWT said:

I would be disappointed with that level of consumption, you use more in your 3 bed mid-terrace than we do in our 5 bed detached, and we have the thermostat higher than you, but ... I'll bet there are some things you can do to improve on that given the age of the property.

How many radiators do you have? That boiler looks a bit over-sized for a 3 bed property, which will make it harder for it to run efficiently, but there may be reasons for it if your installer did a proper job in determining the output required, or not, if that just happened to be what he had available in stock

I chose the boiler using online calculators and the online installer Boxt, sadly we were in a rush as the old boiler died suddenly and we had a 4 week old in the house. However, he didn't raise concerns on installation. 

We have 10 radiators in total:

• x2  small Type 11's in the Kitchen
• x2 old, non-convection 2.3 meter x 600cm doublers. 
• x3 1.3m x 600cm, old single non-convection radiators. 
• x1 towel rail
• x2 Type 21 [1.2m x 600cm]

I am planning on upsizing in the kitchen, and replacing all of the old radiators throughout with either column style or Type 21/22. 

Barmy_Army_92

BUFF said:

MWT said:

 That boiler looks a bit over-sized for a 3 bed property, which will make it harder for it to run efficiently, but there may be reasons for it if your installer did a proper job in determining the output required, or not, if that just happened to be what he had available in stock

If it's a combi it will be for DHW flow rate.

Yes, it is a Combi. From recollection, the CH was 24kw. I think enough to power about 15 radiators, we have ten. 

matelodave

Certainly do something abought drafts and upping the loft insulation but I suspect that a Victorian house wont have cavities to fill (that's where EPC's are a bit useless - they don't take into account stuff that's impossible to do, especially if the surveyor didn't have much of a clue)

If you are going to replace the radiators makes sure  that they are sized to run with a low flow temperature so you can get the boiler flow temp down as low as possible. Running the boiler between 40-50 degrees will save you a lot compared with running it at 60-80. Same with hot water reduce the temp to a max of 60 degrees

BUFF

Barmy_Army_92 said:

Thanks for the responses so far, our EPC recommends cavity insulation to save an estimated 2-3k kWh per year in heating costs. Before any changes, the EPC calculated space and water heating as requiring 17,500 kWh per year. I think with the new boiler and room thermostat we are already on course to dip below that 17.5K, and upgrading loft insulation/cavity wall insulation is getting considered prior to next winter. 

MWT said:

I would be disappointed with that level of consumption, you use more in your 3 bed mid-terrace than we do in our 5 bed detached, and we have the thermostat higher than you, but ... I'll bet there are some things you can do to improve on that given the age of the property.

How many radiators do you have? That boiler looks a bit over-sized for a 3 bed property, which will make it harder for it to run efficiently, but there may be reasons for it if your installer did a proper job in determining the output required, or not, if that just happened to be what he had available in stock

I chose the boiler using online calculators and the online installer Boxt, sadly we were in a rush as the old boiler died suddenly and we had a 4 week old in the house. However, he didn't raise concerns on installation. 

We have 10 radiators in total:

• x2  small Type 11's in the Kitchen
• x2 old, non-convection 2.3 meter x 600cm doublers. 
• x3 1.3m x 600cm, old single non-convection radiators. 
• x1 towel rail
• x2 Type 21 [1.2m x 600cm]

I am planning on upsizing in the kitchen, and replacing all of the old radiators throughout with either column style or Type 21/22. 

as matelodave says you probably will have solid walls rather than a cavity. Be careful that you don't cause damp issues by using inappropriate insulation - your walls/house needs to breathe.

Did Boxt flush your system fully before installing your new boiler (this affects your manufacturer warranty)? Check what flow/return temps your boiler is running - the return needs to be 55C or lower for the boiler to actually condense.

I would definitely be looking at changing the older rads. Modern convectors will use lower water capacities & also release wall space (esp. 22s) for an equivalent output. Columns will take longer to warm up & cool down (as well as being more expensive to buy & harder to clean).

Coffeekup

Is it alot? Yes it's on the heavy side however..

I have lived in my 2 bed mid terraced for a number of year's. Around 12 years ago I started having issues with bills, either bing massively in credit or massively owing, I never switched and was with the same company for years, I was constantly having DD's going up and down.
I came to the conclusion I'll get to the bottom of it as they didn't seem to have an idea what I was using and being charged,I had no idea either.

From then on I did monthly reads of my meters, tapped down the figure's in a spread sheet. First couple of year's my ex partner and our youngest was living here. We used 18,000 kwh's of gas per year and never thought anything of it, admittedly fuel was cheaper back then. 
Then around 9 years ago we stayed away for for 3 weeks in winter when I came back I was shocked to find that months gas usage was so little and saved around £80 in costs that month. It then It dawned on me to cut the cost we need to bring down the usage. Within a couple of years I was using 12,000kwh a year.

Looking back I wasted alot of heating by leaving heating on at night in bed whilst asleep, leaving it on whilst going shop or visit people. Heating on for 2 hours in morning so I could be warm whilst I brushed my teeth and buggered off to work within 15 minutes of being out of bed. Long shower's 2 times a day, also some if it was having heating on for the little one, as my ex always thought temps of 1-3C was 40 below and we'd be blocks of ice within the hour.

Anyhow she left a few years ago so it's just me and the lil one, we average 9,000 a year now for gas now and this year with prices going up since autumn I made a conscious decision to be tighter with the gas usage, fortunately we had a mild autumn winter and buy the time my contract is up in August/September Ill have almost halved that to 5000 units.

I have also had loft insulation, a new boiler that replaced the 25 year old one and single glazing replaced with double glazing.
Did they make a difference to my bills? Maybe saved me 2,000 units a year, wasn't noticable. I did notice less draughts and the heat stays in the house a bit longer when the heating is off, but only by 20 minutes. 

Barmy_Army_92

matelodave said:

Certainly do something abought drafts and upping the loft insulation but I suspect that a Victorian house wont have cavities to fill (that's where EPC's are a bit useless - they don't take into account stuff that's impossible to do, especially if the surveyor didn't have much of a clue)

If you are going to replace the radiators makes sure  that they are sized to run with a low flow temperature so you can get the boiler flow temp down as low as possible. Running the boiler between 40-50 degrees will save you a lot compared with running it at 60-80. Same with hot water reduce the temp to a max of 60 degrees

I actually had the boiler set at 72 degrees. Reduced that to 65 last night without even noticing a difference in performance. Whats the best way of calculating the correct sized radiator to run the boiler at say 50-55? Am I looking for the BTU rating at T30? In some rooms I may be able to oversize the radiators this way, but in others it may not be so easy. Could I use TRV's to reduce the flow to the oversized, and have the normal sized with a fully open TRV? For aesthetics, in some rooms I am consering column radiators [probably 2-3 in total] would they work well in such a system?

QrizB

Barmy_Army_92 said:

I actually had the boiler set at 72 degrees. Reduced that to 65 last night without even noticing a difference in performance. Whats the best way of calculating the correct sized radiator to run the boiler at say 50-55?

The required heat input to a property (or a room in a property) depends on the outside temperature. Radiators should normally be sized to keep your house warm throughout a prolonged cold spell, but this means they will be oversized at all other times.

Rather than replacing your radiators so you can run your boiler at 55 deg. all the time, it's probably more cost effective to keep the radiators you've got and simply turn the flow temperature back up is the weather turns cold. Yes you'll lose a couple of percent of boiler efficiency but that's cheaper than buying new radiators.

I'm currently running my boiler at 50-55C flow temp without other changes. This past winter has been fairly mild and there have only been a few days where I've had to turn the temperature up to 60-65C.

Of course if you're planning to buy new radiators anyway, the extra cost of larger ones might be worth doing.