Baxi multiheat 1.5 wood pellet boiler - known problems

MAJJ

Hi Folks,

Really need some help on behalf of my folks, they have a new build 1.5 years in it, built with energy efficiency in mind from the off which was built into the fabric of the house, concrete with internal/external insulation, air tightness test, heat recovery vents, solar panels, underfloor heating and a very hungry boiler.

I'm getting all my information from my father who it has to said may have some details wrong but he is worried hugely about the cost and usage of pellets. They currently use bags and are in the process of switching to bulk.

This is based on a house of 1800 square feet, with two older adults using average amounts of hot water and most of the zones turned to the minimum. The main thermostat is set to 15 degrees and the other zones have controls to change plus or minus 4 degrees of the main thermostat temp.

I ascertained that the house is looking to maintain 15 degrees 24/7 with an increase of about 2 degrees in the evening in the main living area.

I have been told that the usage in about 3.5 weeks is approx 100 bags or 1 tonne. Since they bought the boiler it seems to be consuming more fuel, it is cleaned regularly both ashes and rods.

They have been told unofficially that the boiler they have is based on an old inefficient design and the model is being replaced with new boilers in new install.

Based on the above 'facts' - does this sound like a problem? For the size of the house is the usage too much, he is convinced he is using twice what he should be.

Thanks for taking the time to read. I'm no expert and need your help.
majj

rayh

MAJJ wrote: »

Hi Folks,

Really need some help on behalf of my folks, they have a new build 1.5 years in it, built with energy efficiency in mind from the off which was built into the fabric of the house, concrete with internal/external insulation, air tightness test, heat recovery vents, solar panels, underfloor heating and a very hungry boiler. - how do you conclude its the boiler is hungry?

I'm getting all my information from my father who it has to said may have some details wrong but he is worried hugely about the cost and usage of pellets. They currently use bags and are in the process of switching to bulk.

This is based on a house of 1800 square feet - detached, semi-detached, terraced, single storey, two storey, multi storey, apartment ? - with two older adults using average amounts of hot water and most of the zones turned to the minimum. - What has the number of occupants got do with the problem? - The main thermostat is set to 15 degrees and the other zones have controls to change plus or minus 4 degrees of the main thermostat temp.

I ascertained that the house is looking to maintain 15 degrees 24/7 with an increase of about 2 degrees in the evening in the main living area.

I have been told that the usage in about 3.5 weeks is approx 100 bags or 1 tonne - generally supplied in 15 or 18kg bags which would yeild nearly 2 tonne of 100 bags ? - Since they bought the boiler it seems to be consuming more fuel, it is cleaned regularly both ashes and rods.

They have been told unofficially that the boiler they have is based on an old inefficient design and the model is being replaced with new boilers in new install.

Based on the above 'facts' - does this sound like a problem? For the size of the house is the usage too much, he is convinced he is using twice what he should be.

Thanks for taking the time to read. I'm no expert and need your help.
majj

MAJJ - Is this a real problem?

Energysaver

MAJJ - I have a 2200 sq ft house and have used about 7.5 tonnes over the last 12 months and I think that is high. I was expecting something like 4 tonnes but maybe I was being optimistic. 1 tonne in 3.5 weeks sounds a bit high, but if it's the last 3.5 weeks then that may not be too far off since it's been very cold. I reckon I've used about 1 tonne in the last month, but I have a bulk pellet silo and so it's hard to judge accurately. My boiler provides the central heating and all the hot water (including showers) for my family of 4. Heating is 18 deg C in all rooms except 21 deg C in sitting room.

Chimpster

MAJJ wrote: »

Hi Folks,

Really need some help on behalf of my folks, they have a new build 1.5 years in it, built with energy efficiency in mind from the off which was built into the fabric of the house, concrete with internal/external insulation, air tightness test, heat recovery vents, solar panels, underfloor heating and a very hungry boiler.

I'm getting all my information from my father who it has to said may have some details wrong but he is worried hugely about the cost and usage of pellets. They currently use bags and are in the process of switching to bulk.

This is based on a house of 1800 square feet, with two older adults using average amounts of hot water and most of the zones turned to the minimum. The main thermostat is set to 15 degrees and the other zones have controls to change plus or minus 4 degrees of the main thermostat temp.

I ascertained that the house is looking to maintain 15 degrees 24/7 with an increase of about 2 degrees in the evening in the main living area.

I have been told that the usage in about 3.5 weeks is approx 100 bags or 1 tonne. Since they bought the boiler it seems to be consuming more fuel, it is cleaned regularly both ashes and rods.

They have been told unofficially that the boiler they have is based on an old inefficient design and the model is being replaced with new boilers in new install.

Based on the above 'facts' - does this sound like a problem? For the size of the house is the usage too much, he is convinced he is using twice what he should be.

Thanks for taking the time to read. I'm no expert and need your help.
majj

If you hadn't said that the house was air tight with mech vent and was well insulated then it could have been a heat loss issue. Its obvious that the boiler is the problem otherwise. Was is sized correctly? Is there a buffer tank? Can Baxi/Heat Merchants/installer offer any advice? Was the pipe insulated from the garage to the house? Is the boiler sufficently insulated?

1 tonne a month is approx the same as 500 litres of oil a month. If your stats are set as low as you say then thats an extremly high usage.

Are you sure the stats are working?

MAJJ

Hi Folks,

Energysaver/Chimpster thank you both for your response.

Chimpster- there is a buffer tank, from BAXIs site the boiler matches the sq footage of the house closely, boiler is out in a shed but no it's not insulated. The stats could be wrong in fact much of what I'm being told could be wrong as it's been related to me from my Dad and some of this is over his head. The house feels as cold as those stats but bottom line I agree it needs further attention from Baxi and co.


Rayh - thanks for all the trouble you went to, this area must be close to your heart. This is a genuine issue posted with the best intentions and I have no other agenda except to help my folks. I choose my words carefully highlighting specifics when known and doubt when vague. All the info has been relayed by my father and I can't independently check all of this. The 'facts' that you highlighted, notice the ' ' in the original post? That was to emphasise that all the facts may not all be accurate. I was trying to ascertain if there was a general problem with the boiler or even was there any problem at all.

Thanks,
Majj

MicktheMan

MAJJ wrote: »

Hi Folks,

Energysaver/Chimpster thank you both for your response.

Chimpster- there is a buffer tank, from BAXIs site the boiler matches the sq footage of the house closely, boiler is out in a shed but no it's not insulated. The stats could be wrong in fact much of what I'm being told could be wrong as it's been related to me from my Dad and some of this is over his head. The house feels as cold as those stats but bottom line I agree it needs further attention from Baxi and co.


Rayh - thanks for all the trouble you went to, this area must be close to your heart. This is a genuine issue posted with the best intentions and I have no other agenda except to help my folks. I choose my words carefully highlighting specifics when known and doubt when vague. All the info has been relayed by my father and I can't independently check all of this. The 'facts' that you highlighted, notice the ' ' in the original post? That was to emphasise that all the facts may not all be accurate. I was trying to ascertain if there was a general problem with the boiler or even was there any problem at all.

Thanks,
Majj

How far is the shed from the house and what type of flow/return piping was used to link the boiler in the shed to the house?

rayh

MAJJ wrote: »

Hi Folks,

Rayh - thanks for all the trouble you went to, this area must be close to your heart. This is a genuine issue posted with the best intentions and I have no other agenda except to help my folks. I choose my words carefully highlighting specifics when known and doubt when vague. All the info has been relayed by my father and I can't independently check all of this. The 'facts' that you highlighted, notice the ' ' in the original post? That was to emphasise that all the facts may not all be accurate. I was trying to ascertain if there was a general problem with the boiler or even was there any problem at all.

Thanks,
Majj

Sorry if my response appeared be critical of your query, but it appeared to me that you had concluded that the Baxi was the cause of your problem, while to me it looked the reverse could possible be the case.

In providing a heat source for our living environs, two issues are presented.

(1) The HEAT LOAD required to meet the losses in the building fabric. Our homes are basically heat leaking enclosures into which we pump heat energy and the resultant temperature is a balance between the rate of input and the rate of leakage and this latter value is related to the temperature differance between inside and outside the house. In the recent cold spell we were seeing temperature differances in the mid twenties Kelvin (Centigrade)

(2) The capacity of the HEAT SOURCE and in this case the Baxi pellet boiler. This device has been designed to provide a specific amount of heat.

Against this background and as in your case, the Heat Source does not match the Heat Load. Therefore, can I suggest that if you are satisfied that your Baxi is generally working to its capacity, that you have an Energy Audit carried out to measure the heat load of the building fabric before attempting to have any measurement of the Baxi performance.

fishfoodie

rayh wrote: »

In the recent cold spell we were seeing temperature differances in the mid twenties Kelvin (Centigrade)

:eek:

I think you might mean Celsius, not Kelvin.