Massive gas bills!17yr old boiler - to replace, or not to replace? That is the question.

housebuyer143

ThisIsWeird said:

FreeBear said:

ThisIsWeird said: 4) Your main house has a Thermostat and Programmer in the hall? Are they a combined unit - a Prog Stat? That may be a source of improvement, but again unlikely to be transformative.

Some research done on energy savings to be had from a fully programmable thermostat (one that allows for different temperatures throughout the day/week) suggests that you could save as much as 15%. In reality, the saving is likely to be around 5%.  Even a few percentage points saved on 100kWh per day would pay for a Tado or Wiser fairly quickly. Although I'm not using anywhere near that much gas, I reckon I saved around 10% with smart controls on an old Baxi back boiler.

Which system would you recommend? Is one better or more affordable than the other? Are they both Opentherm or similar? Could they cope with, say, 15 Smart TRVs, or is it best to split them - eg, extension certainly, but then upstairs-downstairs?
Ta.

Everyone is talking about smart TRVs but in reality, if the OP is only using the heating in 2 hours/3 hour blocks twice a day, then the house will likely never get above 16 degrees in the depths of winter - and what use are the TRVs then?

ComicGeek

Unless the house is really well insulated and airtight (ie a house less than 15 years old), short periods of heating are not effective in keeping a house warm. Most of the heat will be going into warming up cold external walls, and you will never 'feel' warm until room surface temperatures are higher. Once the heating is turned off then those surfaces get cold again, and it feels like the heating hasn't been effective. It can take a couple of days of continuous heating to get the building fabric warm, and then needs to kept on to keep it warm - on a really cold day a couple of hours heating is not enough to get the house warm.

If you want to be warm then the heating needs to be on longer, which costs money. Or you come up with a different strategy, like only heating specific rooms more and keeping the rest of the house at a lower temperature. Or using an electric radiant heater for a key room, which will be cheaper than running the whole central heating system. Or using a fireplace if you have access to cheap wood. 

If you want to save money then the heating hours need to be restricted, and it will be cold at times. That is the problem with older properties.

Any money should be spent on insulation and heating controls. A new boiler isn't going to help.

Ectophile

The new boiler is perhaps 1 to 2% more efficient.  That's a tiny improvement, given the cost of the boiler.

Have you done any checks for gas leaks or a faulty meter?

On a warmer day, try turning the heating off and see what the meter does over a period of a few hours.  If it goes up even when you're not using gas then you either have a gas leak or the meter is faulty.

If it does go up when it shouldn't, then again turn the boiler off, then turn off the main valve next to the meter.

• Meter goes up when the valve is on, but not when it's off - you have a gas leak.
• Meter goes up even if the valve is off, you have a faulty meter.  Expect a long battle with the energy supplier to get the meter formally tested.
  

Albermarle

Everyone is talking about smart TRVs but in reality, if the OP is only using the heating in 2 hours/3 hour blocks twice a day, then the house will likely never get above 16 degrees in the depths of winter - and what use are the TRVs then?

I assumed the OP meant the heating was on for 3 hours a day during October . I presume it will be on longer when the weather is colder, otherwise will be pretty cold like you say.

Unless the house is really well insulated and airtight (ie a house less than 15 years old), short periods of heating are not effective in keeping a house warm. Most of the heat will be going into warming up cold external walls, and you will never 'feel' warm until room surface temperatures are higher.

This is very true, especially if daytime/nightime temperatures are hovering around zero.
In these conditions I do not have the heating fully off for more than about 6 hours at night, and maybe a couple of hours in the day. Once the house is allowed to get cold it can be difficult to get it warm again.

onomatopoeia99

PBD113 said:

Hi all,

I've recently moved into a 2,800 sq. ft. 1920s detached house in the Midlands. The house has an older boiler, and I'm seeking advice on whether replacing it would help reduce my high gas consumption. Currently, I’m averaging 100 kWh/day with 3 hours of central heating and 1 hour of hot water usage. The thermostat is set to 19°C

For comparison, I live in  a 3 bed 1951 detatched bungalow approximately 1/3 the flor area of your enormous mansion.  My boiler is a combi but similar age and efficiency to yours and last week I used 300kWh, which is 43/day.  Multiply that up by area and you get to 130kWh/day, significantly more than your 100/day.  I run the heating at 19C 7am to 10pm and 15C outside those times, so it should be more.

I have 275mm loft insulation, self-installed as it's a zero skill job that even a person with a disability like me can do, cavity wall insulation (paid for that as it's not really DIYable), double glazing (already present) and much better insualating front and rear doors than when I moved in - the front door was the original single glazed type 10 from 1951 which let in plenty of light and let out plenty of heat so I replaced that with a 77mm thick Hormann steel door, the rear door was 1" thick wood with six single glazed panes at the top which I replaced with a composite + double glazed item.

There are 8 radiators + towel radiator in the bathroom, all with TRVs, although two are essentially unused as I've installed wet UFH in those rooms while refurbishing them. I'm able to run the heating circuit at 45-50C (I'm told the lower I can run it the more efficient the boiler gets) unless it gets below -3C outside.  I'm wondering if due to the short amount of time you run the heating for you have to run the boiler hotter to get the house up to temperature in a timely manner?

Insulate, insulate, insulate is my suggestion.  If it's single skinned construction you might want to consider using  cellotex type board on the insides of the external walls, the house is big enough to cope with a small reduction in room sizes. I didn't see you mention the loft, but if you haven't got loft insulation to modern standards (it was 275mm of the glassfibre roll when I did it, don't kow the current standard) then do that it's a simple job you can do yourself if you can use scissors, albeit time consuming and a bit unpleasant.  You mention eaves, I know from experience of my parents' house that the walls that adjoin the eaves get really cold in winter so they should be insulated too, as should whatever provides access.  Loads of cold air blasts in around one of the hatches in my parents house.

FreeBear

ThisIsWeird said:

FreeBear said:

ThisIsWeird said: 4) Your main house has a Thermostat and Programmer in the hall? Are they a combined unit - a Prog Stat? That may be a source of improvement, but again unlikely to be transformative.

Some research done on energy savings to be had from a fully programmable thermostat (one that allows for different temperatures throughout the day/week) suggests that you could save as much as 15%. In reality, the saving is likely to be around 5%.  Even a few percentage points saved on 100kWh per day would pay for a Tado or Wiser fairly quickly. Although I'm not using anywhere near that much gas, I reckon I saved around 10% with smart controls on an old Baxi back boiler.

Which system would you recommend? Is one better or more affordable than the other? Are they both Opentherm or similar? Could they cope with, say, 15 Smart TRVs, or is it best to split them - eg, extension certainly, but then upstairs-downstairs?
Ta.

I don't have a Tado or Wiser, so can't comment on which is better. I have heard that not all versions of the Tado support OpenTherm, so it is prudent to ask the question before purchasing (same for Wiser). Smart TRVs - I'm on the fence on them. Whilst a useful for zoning large systems, to get the best out of them requires a decent home automation system. Preferably one that does not rely on the internet. Unfortunately, most TRVs need you to install an app to do the scheduling (with the right hardware, most can connect to an in house automation system). Unless you are tech savvy, getting these things to work effectively could be a very steep learning curve.

onomatopoeia99 said: I'm able to run the heating circuit at 45-50C (I'm told the lower I can run it the more efficient the boiler gets) unless it gets below -3C outside.

Fitted a heat meter to my CH system earlier in the year to monitor just how much heat is being generated & used. Now that I can pull data from the gas meter, it isn't too difficult to get an idea of actual efficiency. Currently running with a flow temperature of 40-50°C, and it looks like efficiency is around 87%. According to the specs on the boiler (Viessmann 050) I should be at 94-98%. Just waiting for some cold weather to do more testing.

jennifernil

PBD113 said:

Hi all,

I've recently moved into a 2,800 sq. ft. 1920s detached house in the Midlands. The house has an older boiler, and I'm seeking advice on whether replacing it would help reduce my high gas consumption. Currently, I’m averaging 100 kWh/day with 3 hours of central heating and 1 hour of hot water usage. The thermostat is set to 19°C.

Current Boiler Setup:

• Model: Potterton Promax 30 SL (installed in 2007)
• Output: 30.18 kW / 102,980 BTU/hr
• Gas rate: 2.95 m³/hr
• Efficiency: SEDBUK (2005) 90.9%
• Type: System boiler, connected to a recently upgraded unvented tank and well-maintained system
• Heating Zones:
  • Main zone controlled by thermostat and programmer in the hall
  • Extension with 4 radiators controlled by a mobile programmer (Center EHE0200361)

House Characteristics:

• Mix of wall types, mostly solid brick with some cavity insulation
• Double glazing throughout
• Insulated eaves with varying levels of insulation (Celotex and loft rolls)
• 21 radiators, including 3 towel rails, equally split between upstairs and downstairs

Energy-Saving Steps Already Taken:

• Draught-proofing
• Replacing all TRVs
• Turning off heating in unused rooms
• Balancing and bleeding radiators
• Optimizing CH/HW schedule (currently: CH 05:00-07:00 and 16:30-18:00, HW 04:30-05:00 and 16:30-17:00)

Potential Replacement:

I'm considering the Ideal Vogue Max 32 with a 32 kW output and a gas consumption rate of 3.314 m³. Its SEDBUK efficiency is 89.3% (91.1% based on 2005 standards).

My Question:

Would replacing the boiler help reduce gas consumption? Although the new boiler has a higher gas consumption on startup, it should modulate down—could this lead to quicker heating and therefore lower overall gas use? Is the newer boiler more efficient than my current one?

I’m also exploring the option of installing smart TRVs, which might cost around half of what a new boiler would.

Any advice or suggestions would be greatly appreciated!

Thanks in advance.

Our house is also 2800 sq ft, but dates from 1988, timber frame with brick outer skin, well insulated for when it was built, but not as well insulated as today’s new properties.   It is south facing with large windows so a lot of solar gain possible.  It is located NW of Glasgow.

We replaced  both our 33/35 year old boilers in the last couple of years, and also added tado systems with smart TRVs.

The original boilers were Potterton Neataheats, both were still working faultlessly, as they always had done, HW was /still is via well insulated vented cylinders, all but 2 radiators had manual TRVs, 22 radiators in total.   There were also 2 time clocks.

We decided to replace the boilers as they were undoubtedly inefficient by today’s standards, and gas had gone up in price so much.  We also wanted to renew them while we were still allowed to.

We had heating on for 3 hours in the morning and 5 or 6 hours in the evening, plus as we are retired and at home a lot, any time during the day when we felt cold.   There are only the 2 of us here most of the time these days.       

We run at 22 degrees in the living area and our   bathroom, 19 degrees in the hall, kitchen, toilet etc, 16 degrees in bedrooms, and overnight 14 degrees  everywhere.  Our main living room and upper hallway have double height  ceilings, HW, for medical reasons, was on 24 hours.

We used around 28500 kWh of gas annually.

We now have 2 Viessmann 100 heat only boilers and the time clocks and manual TRVs have been replaced by the 2 tado  systems with smart TRVs.  These can call for heat as required and turn on the boilers.  We had to replace our main HW cylinder so now have one that is super insulated.

We have cut down the HW to about 3/4 hours per day, spread over  4/5 different time slots, but the time we heat the house for has not reduced, if anything it has increased ,  though we do now programme each room more accurately, which I think has significantly contributed to the reduction in gas use.

We now use 17500 kWh of gas annually.

I think you should first upgrade your insulation as much as possible, then improve your control system,  then see how that affects your usage,  before replacing your  boiler.

MeteredOut

Very unlikely to be the case, but also check that the gas meter is not faulty.

Otherwise, as stated by others, I'd suggest spending money on insulation rather than a new boiler would be more prudent.

Albermarle

jennifernil said:

PBD113 said:

Hi all,

I've recently moved into a 2,800 sq. ft. 1920s detached house in the Midlands. The house has an older boiler, and I'm seeking advice on whether replacing it would help reduce my high gas consumption. Currently, I’m averaging 100 kWh/day with 3 hours of central heating and 1 hour of hot water usage. The thermostat is set to 19°C.

Current Boiler Setup:

• Model: Potterton Promax 30 SL (installed in 2007)
• Output: 30.18 kW / 102,980 BTU/hr
• Gas rate: 2.95 m³/hr
• Efficiency: SEDBUK (2005) 90.9%
• Type: System boiler, connected to a recently upgraded unvented tank and well-maintained system
• Heating Zones:
  • Main zone controlled by thermostat and programmer in the hall
  • Extension with 4 radiators controlled by a mobile programmer (Center EHE0200361)

House Characteristics:

• Mix of wall types, mostly solid brick with some cavity insulation
• Double glazing throughout
• Insulated eaves with varying levels of insulation (Celotex and loft rolls)
• 21 radiators, including 3 towel rails, equally split between upstairs and downstairs

Energy-Saving Steps Already Taken:

• Draught-proofing
• Replacing all TRVs
• Turning off heating in unused rooms
• Balancing and bleeding radiators
• Optimizing CH/HW schedule (currently: CH 05:00-07:00 and 16:30-18:00, HW 04:30-05:00 and 16:30-17:00)

Potential Replacement:

I'm considering the Ideal Vogue Max 32 with a 32 kW output and a gas consumption rate of 3.314 m³. Its SEDBUK efficiency is 89.3% (91.1% based on 2005 standards).

My Question:

Would replacing the boiler help reduce gas consumption? Although the new boiler has a higher gas consumption on startup, it should modulate down—could this lead to quicker heating and therefore lower overall gas use? Is the newer boiler more efficient than my current one?

I’m also exploring the option of installing smart TRVs, which might cost around half of what a new boiler would.

Any advice or suggestions would be greatly appreciated!

Thanks in advance.

Our house is also 2800 sq ft, but dates from 1988, timber frame with brick outer skin, well insulated for when it was built, but not as well insulated as today’s new properties.   It is south facing with large windows so a lot of solar gain possible.  It is located NW of Glasgow.

We replaced  both our 33/35 year old boilers in the last couple of years, and also added tado systems with smart TRVs.

The original boilers were Potterton Neataheats, both were still working faultlessly, as they always had done, HW was /still is via well insulated vented cylinders, all but 2 radiators had manual TRVs, 22 radiators in total.   There were also 2 time clocks.

We decided to replace the boilers as they were undoubtedly inefficient by today’s standards, and gas had gone up in price so much.  We also wanted to renew them while we were still allowed to.

We had heating on for 3 hours in the morning and 5 or 6 hours in the evening, plus as we are retired and at home a lot, any time during the day when we felt cold.   There are only the 2 of us here most of the time these days.       

We run at 22 degrees in the living area and our   bathroom, 19 degrees in the hall, kitchen, toilet etc, 16 degrees in bedrooms, and overnight 14 degrees  everywhere.  Our main living room and upper hallway have double height  ceilings, HW, for medical reasons, was on 24 hours.

We used around 28500 kWh of gas annually.

We now have 2 Viessmann 100 heat only boilers and the time clocks and manual TRVs have been replaced by the 2 tado  systems with smart TRVs.  These can call for heat as required and turn on the boilers.  We had to replace our main HW cylinder so now have one that is super insulated.

We have cut down the HW to about 3/4 hours per day, spread over  4/5 different time slots, but the time we heat the house for has not reduced, if anything it has increased ,  though we do now programme each room more accurately, which I think has significantly contributed to the reduction in gas use.

We now use 17500 kWh of gas annually.

I think you should first upgrade your insulation as much as possible, then improve your control system,  then see how that affects your usage,  before replacing your  boiler.

Just switching from 35 years old  non condensing boilers to new condensing boilers, will have probably contributed to about half of the savings at least.
Although you have a large house and are in most of the time, the fact there are only two of you means I guess that a lot of the radiators are off/on low ?

ThisIsWeird

Albermarle said:

jennifernil said:

PBD113 said:

Hi all,

I've recently moved into a 2,800 sq. ft. 1920s detached house in the Midlands. The house has an older boiler, and I'm seeking advice on whether replacing it would help reduce my high gas consumption. Currently, I’m averaging 100 kWh/day with 3 hours of central heating and 1 hour of hot water usage. The thermostat is set to 19°C.

Current Boiler Setup:

• Model: Potterton Promax 30 SL (installed in 2007)
• Output: 30.18 kW / 102,980 BTU/hr
• Gas rate: 2.95 m³/hr
• Efficiency: SEDBUK (2005) 90.9%
• Type: System boiler, connected to a recently upgraded unvented tank and well-maintained system
• Heating Zones:
  • Main zone controlled by thermostat and programmer in the hall
  • Extension with 4 radiators controlled by a mobile programmer (Center EHE0200361)

House Characteristics:

• Mix of wall types, mostly solid brick with some cavity insulation
• Double glazing throughout
• Insulated eaves with varying levels of insulation (Celotex and loft rolls)
• 21 radiators, including 3 towel rails, equally split between upstairs and downstairs

Energy-Saving Steps Already Taken:

• Draught-proofing
• Replacing all TRVs
• Turning off heating in unused rooms
• Balancing and bleeding radiators
• Optimizing CH/HW schedule (currently: CH 05:00-07:00 and 16:30-18:00, HW 04:30-05:00 and 16:30-17:00)

Potential Replacement:

I'm considering the Ideal Vogue Max 32 with a 32 kW output and a gas consumption rate of 3.314 m³. Its SEDBUK efficiency is 89.3% (91.1% based on 2005 standards).

My Question:

Would replacing the boiler help reduce gas consumption? Although the new boiler has a higher gas consumption on startup, it should modulate down—could this lead to quicker heating and therefore lower overall gas use? Is the newer boiler more efficient than my current one?

I’m also exploring the option of installing smart TRVs, which might cost around half of what a new boiler would.

Any advice or suggestions would be greatly appreciated!

Thanks in advance.

Our house is also 2800 sq ft, but dates from 1988, timber frame with brick outer skin, well insulated for when it was built, but not as well insulated as today’s new properties.   It is south facing with large windows so a lot of solar gain possible.  It is located NW of Glasgow.

We replaced  both our 33/35 year old boilers in the last couple of years, and also added tado systems with smart TRVs.

The original boilers were Potterton Neataheats, both were still working faultlessly, as they always had done, HW was /still is via well insulated vented cylinders, all but 2 radiators had manual TRVs, 22 radiators in total.   There were also 2 time clocks.

We decided to replace the boilers as they were undoubtedly inefficient by today’s standards, and gas had gone up in price so much.  We also wanted to renew them while we were still allowed to.

We had heating on for 3 hours in the morning and 5 or 6 hours in the evening, plus as we are retired and at home a lot, any time during the day when we felt cold.   There are only the 2 of us here most of the time these days.       

We run at 22 degrees in the living area and our   bathroom, 19 degrees in the hall, kitchen, toilet etc, 16 degrees in bedrooms, and overnight 14 degrees  everywhere.  Our main living room and upper hallway have double height  ceilings, HW, for medical reasons, was on 24 hours.

We used around 28500 kWh of gas annually.

We now have 2 Viessmann 100 heat only boilers and the time clocks and manual TRVs have been replaced by the 2 tado  systems with smart TRVs.  These can call for heat as required and turn on the boilers.  We had to replace our main HW cylinder so now have one that is super insulated.

We have cut down the HW to about 3/4 hours per day, spread over  4/5 different time slots, but the time we heat the house for has not reduced, if anything it has increased ,  though we do now programme each room more accurately, which I think has significantly contributed to the reduction in gas use.

We now use 17500 kWh of gas annually.

I think you should first upgrade your insulation as much as possible, then improve your control system,  then see how that affects your usage,  before replacing your  boiler.

Just switching from 35 years old  non condensing boilers to new condensing boilers, will have probably contributed to about half of the savings at least.
Although you have a large house and are in most of the time, the fact there are only two of you means I guess that a lot of the radiators are off/on low ?

I would actually suspect the Smart TRVs as being of greater benefit, as it sounds as tho Jennifernil had pretty much every room running at at least 14oC at all times, and often at 16oC, even tho they weren't being used?
If that is anywhere still the case, Jennifer, it just isn't necessary - any unused rooms can be left unheated (apart from anti-frost), but well ventilated. They'll be fine.
But, wow, that's some saving!