Heat Pumps - post here.

GreeBo

banie01 wrote: »

The A2W heat pump is likely where I see my next home efficiency upgrade being.

I have a 1980's 3 bed semi and have pumped the walls with bonded bead, topped up the attic and installed triple Glazing.
Have Nest installed and heating rarely runs for more than 1hr a day.
I'm reading with interest the posts on radiators as I can't afford installing ufh and would like to keep as much of my existing equipment as possible and the rads are fairly new.

I'm leaning towards solar hot water, larger hot water tank and A2W. Is there an option to utilise the solar gain for heating? Or is it more efficient to stick with PV and use the electricity to run A2W?

I dont see how you are keeping the house warm with 1hr a day of heating?
What is maintaining the heat in the building if you just have radiators?

Surely once a window or door is opened all the hot air you heated is gone and you are back to square one?

Apologies if I missed you have UFH or something else, but right now I dont get it...:o

Latro

John.G wrote: »

A bit of zoning would help.

He would get some idea if he just monitors (listens) to his oil boiler ON cycle times over say a half or one hour period, if the boiler output is known then it is quite easy to calculate the house requirement. For example I know my boiler gives 20 Kw output. Once the house is up to temperature and obviously depending on ambient temperature it cycles ON for anything between 25% to 40% of time which means my requirements are between 5Kw and 8Kw. I know this is a bit rough and ready but it will certainly give some idea if 12 Kw is sufficient and of course a 12 KW unit will only give 5 or 6 Kw in very cold weather.

You are being way pessimistic here.

My heat pump according to manufacturer at water flow 35C has full 9kW power at +7 outdoor, at +2C it has 7.45kW and at -7C 7.70kW.

Same brand/model but 12kW unit: 12kW at +7, 11.4kW at +2 and 10kW at -7. So at full power run for 24h at -7C and 35 flow it could produce 240kWh of heat and I really doubt he needs anywhere close to that.

Perhaps installing thermostatic mixing valve and let the oil run for a week non stop at 35-40C would answer the question if it suitable for the house or not.

Shouldn't be expensive job. The valve probably 70 euro and labor no more than half day worth of work. But who knows these days, plumbers tend to charge and arm and a leg for their services.

banie01

GreeBo wrote: »

I dont see how you are keeping the house warm with 1hr a day of heating?
What is maintaining the heat in the building if you just have radiators?

Surely once a window or door is opened all the hot air you heated is gone and you are back to square one?

Apologies if I missed you have UFH or something else, but right now I dont get it...:o

Only thing I can think of that's different from standard is an entrance porch.
No UFH and nest set to 20°, I have noticed a lot more solar gain since installing the triple Glazing tho.

Shefwedfan

John.G wrote: »

A bit of zoning would help.

He would get some idea if he just monitors (listens) to his oil boiler ON cycle times over say a half or one hour period, if the boiler output is known then it is quite easy to calculate the house requirement. For example I know my boiler gives 20 Kw output. Once the house is up to temperature and obviously depending on ambient temperature it cycles ON for anything between 25% to 40% of time which means my requirements are between 5Kw and 8Kw. I know this is a bit rough and ready but it will certainly give some idea if 12 Kw is sufficient and of course a 12 KW unit will only give 5 or 6 Kw in very cold weather.

The current boiler is Grant Vortex 36-46 Pro Utility. Now this was installed by previous owner, when lets say the 60% of the house I renovated was an ice box. So I personally think it is oversized now for the house.


The boiler will fire up, fairly soon afterwards if just heating the house will kick off....then it goes in and out to reheat.....no idea how many times or how long it will cycle in & out....

The house is zoned. Image attached, It has 3 zones and then hot water but the zones are manual valve which is kind of pointless. Also they have a single thermostat running all of the zones so the heavy lifting is done so to speak and just need some small upgrade to that.


Just to note from image, the stove is connected to the heating system. One of the installers said the would just disconnect the stove and the A2W would connect into that section. The stove is a Glenmore 30B but on its last legs as previous owner seems to have burned all sorts of s**t in it. So it would be going anyway

John.G

Latro wrote: »

You are being way pessimistic here.

My heat pump according to manufacturer at water flow 35C has full 9kW power at +7 outdoor, at +2C it has 7.45kW and at -7C 7.70kW.

Same brand/model but 12kW unit: 12kW at +7, 11.4kW at +2 and 10kW at -7. So at full power run for 24h at -7C and 35 flow it could produce 240kWh of heat and I really doubt he needs anywhere close to that.

Perhaps installing thermostatic mixing valve and let the oil run for a week non stop at 35-40C would answer the question if it suitable for the house or not.

Shouldn't be expensive job. The valve probably 70 euro and labor no more than half day worth of work. But who knows these days, plumbers tend to charge and arm and a leg for their services.

Yes I was far too pessimistic there, I think Kingspan do a Aeromax 15 KW unit which i presume is single phase but maybe this is only for the UK market.

Jbrod87

I have a Mitsubishi ecodan system and since the weather has gotten colder it turns on in the middle of the night or early evening depending on how cold it is. But the water and heating are turned off but it still comes on. Is this normal? Also the pumps in the hot press are quiet loud when they turn on. Loud enough to wake you up. Thanks

Tefral

Jbrod87 wrote: »

I have a Mitsubishi ecodan system and since the weather has gotten colder it turns on in the middle of the night or early evening depending on how cold it is. But the water and heating are turned off but it still comes on. Is this normal? Also the pumps in the hot press are quiet loud when they turn on. Loud enough to wake you up. Thanks

If your telling me the water and heat are actually off then its the defrost cycle thats happening.

It uses the hot water from the house to defrost the unit.

youcancallmeal

Jbrod87 wrote: »

I have a Mitsubishi ecodan system and since the weather has gotten colder it turns on in the middle of the night or early evening depending on how cold it is. But the water and heating are turned off but it still comes on. Is this normal? Also the pumps in the hot press are quiet loud when they turn on. Loud enough to wake you up. Thanks

Could be a sterilization cycle or even just topping up to maintain water temp

The Engineer

My best friend is considering installing this system too. What did you decide in the end?

BFMadden wrote: »

Guys,

Has anyone any experience of an Ovum heat pump and DHW system? They're an Austrian brand that is supplied and installed by Climate Control in Galway. Looks good but there's very little info on it.

ovum.at

Open link with Chrome to translate.

Thanks

H.E. Pennypacker

I'm looking at retrofitting an A2W heat pump to a 1950's house. My heat loss indicator is within limits for the grant, my air leakage figure is 4.6. The house is a 135 sq meter bungalow, no underfloor heating, just steel radiators. The house is very comfortable with the oil fired boiler turned down to achieve a 40C flow temperature. The boiler runs for a max of 6.5 hours out of 24 to keep the house at a comfortable temperature.

I've had three rough quotes. One suggested a 6 - 8 kWh heat pump, another a 7 - 9 kWh heat pump and the third suggested a 14kWh model. As sizing is critical to getting comfort, running costs and reliability right, is there any way of independently calculating a ballpark suitable size?

Water John

The BER should show the energy use. 14Kw would be too large IWT. A large stove of that size would roast you out of your house.
A 14Kw stove would run 10/12 rads easily at high temp.

H.E. Pennypacker

Water John wrote: »

The BER should show the energy use. 14Kw would be too large IWT. A large stove of that size would roast you out of your house.
A 14Kw stove would run 10/12 rads easily at high temp.

Thanks, so if I had a BER of 135 kWh/m2/yr how do I calculate my heating load vs my total energy consumption and figure out a suitably sized HP from that?

John.G

H.E. Pennypacker wrote: »

I'm looking at retrofitting an A2W heat pump to a 1950's house. My heat loss indicator is within limits for the grant, my air leakage figure is 4.6. The house is a 135 sq meter bungalow, no underfloor heating, just steel radiators. The house is very comfortable with the oil fired boiler turned down to achieve a 40C flow temperature. The boiler runs for a max of 6.5 hours out of 24 to keep the house at a comfortable temperature.

I've had three rough quotes. One suggested a 6 - 8 kWh heat pump, another a 7 - 9 kWh heat pump and the third suggested a 14kWh model. As sizing is critical to getting comfort, running costs and reliability right, is there any way of independently calculating a ballpark suitable size?

IF the boiler is actually firing (as distinct from being "on") for 6.5 hrs per 24 hours then that that means that the boiler is firing for 27% of the time. You don't state what the output of the boiler is but if one uses a figure of 23.4 Kw (80K Btu/hr) then your requirement is, 0.27*23.4, 6.3 Kw, if this includes the hot water requirement then it might suggest that a 9 Kw unit might suffice, you can get a unit with variable speed drive so the 9 Kw or maybe a bit bigger will modulate to your actual requirements.

Re the BER (post 1303), a BER is based as far as I know on the heating, ventilation, water heating and lighting requirements so heating is only part of the calculation so one cannot deduce the heating requirement from the stated BER without knowing at least what the water heating requirement is.
Your water heating requirement will depend on the number of persons and the usage per person. If one assumes 60 Litres of hot water (60C) per person per day, this will require 3.5 Kwh /person/day, a family of 4 will require 14 Kwh/day or 5110 Kwh/year or 37.9 Kwh/M2/annum (water heating portion of the BER?)
I don't know if the BER is based on 365 days/year, one would think so as water heating and lighting are required throughout the year.

H.E. Pennypacker

John.G wrote: »

IF the boiler is actually firing (as distinct from being "on") for 6.5 hrs per 24 hours then that that means that the boiler is firing for 27% of the time. You don't state what the output of the boiler is but if one uses a figure of 23.4 Kw (80K Btu/hr) then your requirement is, 0.27*23.4, 6.3 Kw, if this includes the hot water requirement then it might suggest that a 9 Kw unit might suffice, you can get a unit with variable speed drive so the 9 Kw or maybe a bit bigger will modulate to your actual requirements.

Re the BER (post 1303), a BER is based as far as I know on the heating, ventilation, water heating and lighting requirements so heating is only part of the calculation so one cannot deduce the heating requirement from the stated BER without knowing at least what the water heating requirement is.
Your water heating requirement will depend on the number of persons and the usage per person. If one assumes 60 Litres of hot water (60C) per person per day, this will require 3.5 Kwh /person/day, a family of 4 will require 14 Kwh/day or 5110 Kwh/year or 37.9 Kwh/M2/annum (water heating portion of the BER?)
I don't know if the BER is based on 365 days/year, one would think so as water heating and lighting are required throughout the year.

Thanks again. The 6.5 hours is derived from the Nest stats. Boiler firing time is that or possibly less as it probably reflects heating demand rather than boiler firing time. Its a 15-26kw Grant condensing boiler but I don't know what nozzle is fitted to the burner so not sure of the actual output. Probably close to max. 11 rads here altogether, 3 singles, the rest doubles. Hot water is entirely from immersion on night rate electricity as the boiler flow temp is too low.



It's a four person household so I reckon that your hot water calc is spot on.


So basically, the 14kWh quote sounds like its off the scale.

Latro

H.E. Pennypacker wrote: »

I'm looking at retrofitting an A2W heat pump to a 1950's house. My heat loss indicator is within limits for the grant, my air leakage figure is 4.6. The house is a 135 sq meter bungalow, no underfloor heating, just steel radiators. The house is very comfortable with the oil fired boiler turned down to achieve a 40C flow temperature. The boiler runs for a max of 6.5 hours out of 24 to keep the house at a comfortable temperature.

I've had three rough quotes. One suggested a 6 - 8 kWh heat pump, another a 7 - 9 kWh heat pump and the third suggested a 14kWh model. As sizing is critical to getting comfort, running costs and reliability right, is there any way of independently calculating a ballpark suitable size?

I'd go with 7kW. Most sellers and installers tend to oversize boilers by a lot.


Even with that you will probably rarely see it working at full capacity.


My 9kW HP operates most of the time at between 0.4-0.8 kW consumption at around 4.0 COP. It bumps itself to 2kW for a short time right after the defrost cycle. It is on 24/7.

John.G

H.E. Pennypacker wrote: »

Thanks again. The 6.5 hours is derived from the Nest stats. Boiler firing time is that or possibly less as it probably reflects heating demand rather than boiler firing time. Its a 15-26kw Grant condensing boiler but I don't know what nozzle is fitted to the burner so not sure of the actual output. Probably close to max. 11 rads here altogether, 3 singles, the rest doubles. Hot water is entirely from immersion on night rate electricity as the boiler flow temp is too low.



It's a four person household so I reckon that your hot water calc is spot on.


So basically, the 14kWh quote sounds like its off the scale.

Yes its almost certainly the heating demand rather than the boiler firing time that the Nest is monitoring, if you have the time or the inclination you could monitor the on/off time of the burner over say three or four cycles when the system is up to normal running temperature and just say averaging over a few cycles the burner is on for 5.2 mins and off for 6.8 mins then the output is 43% of say 26 KW or ~ 11 Kw, then that 11 KW for 6.5 hours over a 24 hour period is ~ 3 Kw so as Latro states above, a 7 KW unit would fit the bill in that instance.

randombar

Hi Guys,

Just wondering about some advice.

My uncle recommends converting to a heat pump as a decent investment.

Using roughly 1000 litres of kerosene a year in a B1 rated 2500 square foot well insulated house with radiators upstairs and down.

What kind of costs would we be talking about for an upgrade? Would a HRV be required?

Is there a potential ROI?

Nice one,
Gary

P.S. I'm wondering should I get an energy audit done on the place, any recommendations in Cork?

H.E. Pennypacker

GaryCocs wrote: »

Hi Guys,

Just wondering about some advice.

My uncle recommends converting to a heat pump as a decent investment.

Using roughly 1000 litres of kerosene a year in a B1 rated 2500 square foot well insulated house with radiators upstairs and down.

What kind of costs would we be talking about for an upgrade? Would a HRV be required?

Is there a potential ROI?

Nice one,
Gary

P.S. I'm wondering should I get an energy audit done on the place, any recommendations in Cork?

I've had ballpark quotes from €9k to €17k less grant for air to water. Sounds like you spend between €800 and €1,000 on kerosene so your payback will take a while but if you had a heat pump installed for €7k after the grant it'd be do-able.


HRV might be a good bit of work to retrofit into a two storey house but I'd definitely recommend it if its do-able. It transformed our house and we're not as airtight as a modern house.

randombar

H.E. Pennypacker wrote: »

I've had ballpark quotes from €9k to €17k less grant for air to water. Sounds like you spend between €800 and €1,000 on kerosene so your payback will take a while but if you had a heat pump installed for €7k after the grant it'd be do-able.


HRV might be a good bit of work to retrofit into a two storey house but I'd definitely recommend it if its do-able. It transformed our house and we're not as airtight as a modern house.

Would HRV be a completely separate job to the air2water? What prices would I be looking at for that? Leaving this morning herself has a few windows open for the fresh air etc. Disaster.

I guess the warranty would determine the feasibility of an Air2Water. i.e. if the return takes 10 years and the device has a 5 year warranty it wouldn't make sense.

H.E. Pennypacker

GaryCocs wrote: »

Would HRV be a completely separate job to the air2water? What prices would I be looking at for that? Leaving this morning herself has a few windows open for the fresh air etc. Disaster.

I guess the warranty would determine the feasibility of an Air2Water. i.e. if the return takes 10 years and the device has a 5 year warranty it wouldn't make sense.

I paid €5.5k for HRV retrofitted to a bungalow but that's an easy job with access to all rooms from above. It'd be a bit more work on a two storey house - not sure how that'd be costed.


Not sure of lifespan of A2W heap pumps - I've seen ten years quoted for some components but sizing is critical. Too big or too small and it won't run right with additional stresses on it.

KCross

GaryCocs wrote: »

Would HRV be a completely separate job to the air2water? What prices would I be looking at for that? Leaving this morning herself has a few windows open for the fresh air etc. Disaster.

I guess the warranty would determine the feasibility of an Air2Water. i.e. if the return takes 10 years and the device has a 5 year warranty it wouldn't make sense.

HRV is generally separate.
You would be looking at €5k+ for that job, unless you are handy yourself.

There is no real financial payback for HRV. Yes, it will reduce heat loss and hence your heating bills but it will never pay for itself in any short timeframe. The benefits are fresh filtered air 24/7, so its a health benefit more than a financial one.

On the heat pump, the payback for you is going to be at least 10-15 years based on what you've said.
Lets say it costs €10k to install. If it saves you €700/year in running costs over kerosene it will be 14 years breaking even.

You'd be better spending your money on more insulation, the HRV or Solar PV panels etc.

Latro

GaryCocs wrote: »

Hi Guys,


Using roughly 1000 litres of kerosene a year in a B1 rated 2500 square foot well insulated house with radiators upstairs and down.

If you burn 1000L of oil that means your heat demand is around 8000kWh/year. Assuming you are happy with comfort you have now.

Considering 1 liter of oil today is €0.75, 8000kWh costs you now about €750.
With heat pump same amount of energy would cost you around 8000kWh*€0.16/3=€427
€323 saving a year.

Any air tightness, insulation or ventilation upgrades will improve the situation regardless how the house is heated. I'd consider them first before your oil heating upgrade.

With more stable temperature throughout the day and fresher air your house would not only be cheaper to live in but also more comfortable.

Before you decide to go with a heat pump retrofit one of the important factor is your radiator surface area. It has to be large enough to easy radiate out needed amount of energy over 24h period. The lower the flow temperature the more efficient heat pumps work and on a down side the bigger radiator you need. That's why they work great with underfloor heating.

There are also fan coils that can be fitted in place of existing rads but they are not cheap devices. You wouldn't need to replace all of them though. Perhaps 3-4 would do the job.

randombar

Latro wrote: »

If you burn 1000L of oil that means your heat demand is around 8000kWh/year. Assuming you are happy with comfort you have now.

Considering 1 liter of oil today is €0.75, 8000kWh costs you now about €750.
With heat pump same amount of energy would cost you around 8000kWh*€0.16/3=€427
€323 saving a year.

Any air tightness, insulation or ventilation upgrades will improve the situation regardless how the house is heated. I'd consider them first before your oil heating upgrade.

With more stable temperature throughout the day and fresher air your house would not only be cheaper to live in but also more comfortable.

Before you decide to go with a heat pump retrofit one of the important factor is your radiator surface area. It has to be large enough to easy radiate out needed amount of energy over 24h period. The lower the flow temperature the more efficient heat pumps work and on a down side the bigger radiator you need. That's why they work great with underfloor heating.

There are also fan coils that can be fitted in place of existing rads but they are not cheap devices. You wouldn't need to replace all of them though. Perhaps 3-4 would do the job.

Thanks for that.

Would people think 8000 is high for 2,500 sq feet?

Would be a long return on 300 per year all right.

Contacting a few energy specialists from the SEAI list to maybe do an audit on the place. See where I can save a few quid.

Latro

From top of my head 8000kWh for 230sqm house is very low. You either have very energy efficient house or you just don't heat it much and the comfort is not great but that's subjective term.

randombar

Latro wrote: »

From top of my head 8000kWh for 230sqm house it is very low. You either have very energy efficient house or you just don't heat it much and the comfort is not great but that's subjective term.

Thanks for that, good news I guess. The insulation is pretty decent. 250 mm cavity with 150mm board and 100mm cavity. A rated windows (not triple) and dry lining inside to avoid thermal bridging.

I might sus out a bit more about the hrv, the heat loss we have at the moment is due to the windows being opened for fresh air and air tightness I guess. The front door is warped (replacing) and a bit draughty, wouldn't mind getting the place reviewed after.

H.E. Pennypacker

GaryCocs wrote: »

Thanks for that, good news I guess. The insulation is pretty decent. 250 mm cavity with 150mm board and 100mm cavity. A rated windows (not triple) and dry lining inside to avoid thermal bridging.

I might sus out a bit more about the hrv, the heat loss we have at the moment is due to the windows being opened for fresh air and air tightness I guess. The front door is warped (replacing) and a bit draughty, wouldn't mind getting the place reviewed after.

I had a thermal imaging survey and door blower test done before I did anything to the house - its a really useful way of targetting upgrades. Its important that you understand and address your airtightness weaknesses before you put in HRV. It doesn't have to be perfect but there are usually some quick wins that'll improve comfort.

bluesteel

Supply & fit 12kw Samsung Heat Pump & Heating controls item €10,850.00
Joule 250/60L Pre-Plumbed Samsung Cylinder item €1,900.00

excluses VAT - Pre Grant

I have this quote as part of the deep retrofit scheme. Any thoughts on pricing?

thanks

Latro

bluesteel wrote: »

excluses VAT - Pre Grant

I have this quote as part of the deep retrofit scheme. Any thoughts on pricing?

thanks

That's 13k for heating system.
Did you do any kind of estimation how much running cost it would save you over 10-15 years?
How big is the house, what heating you have now and how much does it cost to run it?

bluesteel

Latro wrote: »

That's 13k for heating system.
Did you do any kind of estimation how much running cost it would save you over 10-15 years?
How big is the house, what heating you have now and how much does it cost to run it?

it's for the Deep Retrofit scheme - the house will be well insulated. It's a typical 3 bed semi-d

I haven't lived in the house for very long - there's oil at the moment which the previous family topped up so I really don't know

There's a good grant level; I need to do other refurb work anyway so it kinda suits to go all in

Latro

bluesteel wrote: »

it's for the Deep Retrofit scheme - the house will be well insulated.

Wouldn't this be enough to keep the running cost low?
You really should go deeper into analysis if it's really worth it.

As you are adding insulation and air tightness the heat loss is slowly approaching 0 and so are potential savings from running the heat pump. 13k+vat? :eek:.
Some people would tell you that the price is ok as long as the house comes with it.

I'm not a big fan of grant systems the way they are now. Most of the benefits if not all are mitigated by extra costs involved with assessments, certifications, commissioning and extra expensive installation done by highly certified shortlisted installer.

Look at the whole solar panels grant system. You'd probably be financially better off not bothering with it.
I don't know if that's the case here, just a food for thought.

Are you planning on going with underfloor and heat recovery ventilation?