combi boiler vs heat pump

s7ryf3925pivug

1970s bungalow with EWI, insulated floors, double glazing. I reckon the double glazing is **** because you can hear someone talking through it v clearly.

Traditional gas boiler that overheats if we turn it past 1, or insulate exposed pipes, or turn off too many radiators. Switching on hot water heating is a big no no and causes the attic to fill with steam through the overflow tank. Worth replacing.

Looking mainly at getting a combi boiler installed. Like the idea of not beeding tanks and having hot water on demand... But wondering if we should look at heat pumps, or even consider applying for a deep retrofit grant. Already planning to install DCV.

Budgeting about 60k on rennovations. Lots of things planned but the three big expenses on the list are building a conservatory at the back, refitting the kitchen, and upgrading the central heating.

Thinking in the long term, is it a better idea to look into a heat pump setup, or is the combi a better fit? Is it likely that the combi will become as strong a candidate for replacement as non-condensing boilers are now, 10 or 15 years down the line?

Xcellor

Merrick Fancy Symbol wrote: »

1970s bungalow with EWI, insulated floors, double glazing. I reckon the double glazing is **** because you can hear someone talking through it v clearly.

Check the hinges. These may need replaced. The hinge should close and seal the window tight, over time these can become weak and may not be working so the seal isn't flush.

s7ryf3925pivug

15k plus new doors and windows for heat pump versus 6k for combi and related work including new piping from tank. We have an external LPG tank that was disconnected and a hazard notice issued since last post.

I suppose the combi option is a no-brainer given the outlay is probably an easy 20k more for the heat pump approach and major renovations would be involved. I'm aware of the deep retrofit grants but can't have no central heating while waiting to try to sort that out. Environmental concerns and future proofing are the only reasons I'm hesitating at all.

Calahonda52

Merrick Fancy Symbol wrote: »

15k plus new doors and windows for heat pump versus 6k for combi and related work including new piping from tank. We have an external LPG tank that was disconnected and a hazard notice issued since last post.

I suppose the combi option is a no-brainer given the outlay is probably an easy 20k more for the heat pump approach and major renovations would be involved. I'm aware of the deep retrofit grants but can't have no central heating while waiting to try to sort that out. Environmental concerns and future proofing are the only reasons I'm hesitating at all.

What are you asking here?

s7ryf3925pivug

Calahonda52 wrote: »

What are you asking here?

Is it crazy to consider a heat pump over a combi, given the additional costs and renovations would be so great?

GreeBo

what additional renovations are you including for the heatpump versus new boiler?
Is it your "forever" home?

s7ryf3925pivug

GreeBo wrote: »

what additional renovations are you including for the heatpump versus new boiler?
Is it your "forever" home?

New windows and doors, as advised by the central heating engineer. We have big windows.

Forever home yes.

Heat pump installation might be prohibitively expensive, regardless whether it's a reasonable choice. My question is whether it is a reasonable choice though.

GreeBo

Merrick Fancy Symbol wrote: »

New windows and doors, as advised by the central heating engineer. We have big windows.

Forever home yes.

Heat pump installation might be prohibitively expensive, regardless whether it's a reasonable choice. My question is whether it is a reasonable choice though.

Will you not need new windows and doors irrespective of the heat source?!

s7ryf3925pivug

GreeBo wrote: »

Will you not need new windows and doors irrespective of the heat source?!

Double glazing and uPVC are in place.... It would be the difference between making new doors and windows an optional improvement and them being a hard requirement for the heating system to work adequately.

We'd need new radiators as well, or underfloor heating. We've screed subfloors so the latter would probably need to be put on top of it.

H.E. Pennypacker

Get someone good out to service your windows and doors, replacing seals & hinges where necessary.

Any idea of what your heat loss indicator from the BER is?

Any idea of your gas consumption for the last year?

Are your options just new LPG tank & boiler, oil tank and oil boiler or heat pump? No grid gas?

s7ryf3925pivug

H.E. Pennypacker wrote: »

Get someone good out to service your windows and doors, replacing seals & hinges where necessary.

Any idea of what your heat loss indicator from the BER is?

Any idea of your gas consumption for the last year?

Are your options just new LPG tank & boiler, oil tank and oil boiler or heat pump? No grid gas?

Good idea to get windows serviced if not replacing them.

No idea about heat loss indicator. Ber rating is low even though we have good insulation. Not sure a new report was done after insulation etc installed. I did fix gaps in attic insulation that might have been a thing.

Gas consumption was artificially high because we had several external leaks (hence the hazard notice and shut off of tank). We have not been in the house a year.

Yes we have no grid connection.

You already seem settled on the combi boiler from reading your posts.

But just to add that I installed a combi boiler about 2 years ago and love it. I also love that I could free up some space by getting rid of the hot tank altogether. It worked out about 6k I believe, for my install, which was to replace the old boiler with the new combi, and install an extra 4 radiators in an extension. I think the boiler + install itself was in and around 5k, with an SEAI grant of about 600 if I recall correctly.

There was a lot going on at the time, extension, etc. so there were numbers flying at me from every direction so I could be wrong on the above numbers, but I'm fairly sure they're somewhat accurate.

Hot water takes about 10-15 seconds to get to you if the boiler is off (though there's an option to set it so it always has hot water on demand, though I think this is pointless for the small amount of hot water use we have day to day). Boiler has a water temperature control independent of the heating, which is good, but can be a bit finicky when you first start messing with it. Somehow the water from our old hot tank was always 'just right', whereas when we got the combi it was a bit of trial and error between scalding yourself and being cold, to get the right balance for showers and washing the dishes etc.

My only regret is not getting it installed sooner. Would never consider a heat pump as the cost is mental, and I'm confident the cost will come down and in 10-20 years they'll either be much much cheaper to install, or replaced with a different technology altogether.

H.E. Pennypacker

Your BER will give you some guidance as to what areas need improvement. If EWI was done, a subsequent BER would have been necessary for the grant. Whoever did the BER should be able to give you the heat loss indicator value. For grant purposes it has to be 2ish so if you're not near that and your BER isn't great then you would be better off putting money into addressing outstanding heat loss and air tightness issues. A heat pump would be too risky in terms of running costs, sizing etc. If you reduce your heat loss then the form of heating that you use becomes less important.

FWIW, I'm getting quotes of €10k to €13k for a retrofit heat pump installation plus €3.5k to €5k to replace around ten radiators to satisfy grant requirements. A new gas/oil setup would be a lot cheaper and you'd have more certainty over effectiveness and costs. The cost gap between heat pump and oil or gas isn't that great once you've sorted heat loss - you'll be reducing your energy consumption and that will go some way towards addressing environmental concerns.

You can always retrofit a heat pump in the future once you've everything else sorted. I'm not sure that now's the right time for you, especially if time is of the essence. A deep retrofit is an alternative option but it'll take time before any work can start.

H.E. Pennypacker

The SEAI fuel costs comparison (https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf) shows just over a 4 cent/kWh difference between kerosene and bulk LPG. That's €600 per year more for LPG assuming that you might use 15,000 KWh so think about that if you're choosing between the two fuels and are looking at introductory offers by gas suppliers.

0lddog

H.E. Pennypacker wrote: »

The SEAI fuel costs comparison (https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf) shows just over a 4 cent/kWh difference between kerosene and bulk LPG. That's €600 per year more for LPG assuming that you might use 15,000 KWh so think about that if you're choosing between the two fuels and are looking at introductory offers by gas suppliers.

And probably a yearly LPG gas tank rental charge on top of the €600 ?

GreeBo

Merrick Fancy Symbol wrote: »

Double glazing and uPVC are in place.... It would be the difference between making new doors and windows an optional improvement and them being a hard requirement for the heating system to work adequately.

We'd need new radiators as well, or underfloor heating. We've screed subfloors so the latter would probably need to be put on top of it.

I still don't get why they would be a hard requirement for a heat pump but not a combi boiler?
Surely if heat is escaping then heat is escaping, irrespective of how it was generated?

Rads are fair enough.

s7ryf3925pivug

GreeBo wrote: »

I still don't get why they would be a hard requirement for a heat pump but not a combi boiler?
Surely if heat is escaping then heat is escaping, irrespective of how it was generated?

Rads are fair enough.

The combi boiler would generate more heat. Heat pumps are high efficiency low output systems that are only suitable for houses that retain heat very well. That's my understanding at least.

GreeBo

Merrick Fancy Symbol wrote: »

The combi boiler would generate more heat. Heat pumps are high efficiency low output systems that are only suitable for houses that retain heat very well. That's my understanding at least.

A boiler will run at a higher temperature than a heat pump, but if the heat is escaping due to leaks then it doesn't really matter.

In fact the greater the differential the faster the heat is going to escape due to thermodynamics.

Your EWI is going to help things due to the thermal mass heating up (assuming you dont also have internal insulation?)

0lddog

Given electric power in is limited and that many A2W have abysmal low outside temps efficiency, understanding the winter heat requirment of the building is essential before trying to spec a heatpump.
On a cold winter day OP can just turn up the heat with oil / gas. Not so easy with a HP

s7ryf3925pivug

GreeBo wrote: »

A boiler will run at a higher temperature than a heat pump, but if the heat is escaping due to leaks then it doesn't really matter.

In fact the greater the differential the faster the heat is going to escape due to thermodynamics.

Your EWI is going to help things due to the thermal mass heating up (assuming you dont also have internal insulation?)

No internal insulation, unless you count fiberglass in the attic.

It's not about which has greater heat loss, it's about the heat pump not being able to keep the house adequately warm if not complimented by excellent insulation - as I understand it.

s7ryf3925pivug

H.E. Pennypacker wrote: »

The SEAI fuel costs comparison (https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf) shows just over a 4 cent/kWh difference between kerosene and bulk LPG. That's €600 per year more for LPG assuming that you might use 15,000 KWh so think about that if you're choosing between the two fuels and are looking at introductory offers by gas suppliers.

Didn't realize that. Still prefer LPG because it's theft-proof, and it has lower emissions. Will ask about biolpg actually with the latter in mind. Looks like it might be as good as a heat pump in that regard - based on my casual and quick research at least

Alkers

Just to add our 2c, we have a combi boiler the last two years also, got the seai grants shorty before they got rid of the option for a new boiler grant. We have a smart thermostat in the hall and individual controls on all the other rads and also a weather compensator (iirc) which allows the boiler to know the outdoor temperature. It's been absolutely amazing, in the summer our gas bill is 30e for two months with four adults in the house.
I can't believe they're not the standard setup, it makes so much more sense than a hot water cylinder. When we did that maths at the time, none of the other options made financial sense at all, solar heating, solar diverter etc you're looking at 20 years for your outlay to payback.

GreeBo

0lddog wrote: »

Given electric power in is limited and that many A2W have abysmal low outside temps efficiency, understanding the winter heat requirment of the building is essential before trying to spec a heatpump.
On a cold winter day OP can just turn up the heat with oil / gas. Not so easy with a HP

With an externally insulated house and a heat pump you dont have warm or cold days, your house just stays at whatever temperature you want it to be all year round... :cool:


Why is electric power in limited?

0lddog

GreeBo wrote: »

With an externally insulated house and a heat pump you dont have warm or cold days, your house just stays at whatever temperature you want it to be all year round... :cool:......

I bet OP would be delighted if that was how his house performed

GreeBo wrote: »

.......Why is electric power in limited?

Suggest that you ask ESB Networks

ercork

GreeBo wrote: »

With an externally insulated house and a heat pump you dont have warm or cold days, your house just stays at whatever temperature you want it to be all year round... :cool:


Why is electric power in limited?

As I understand it heat pumps output about 15kW of heat. If your property is well insulated this is probably plenty heat to keep it at 20 C all day long, or whatever temp you like. However an older, draughtier property would need more heat than this to keep it warm. Gas boilers can produce 30 - 40 kW of heat and would do a better job heating such a place.

GreeBo

0lddog wrote: »

I bet OP would be delighted if that was how his house performed





Suggest that you ask ESB Networks

He already has ewi so that sorts the heat store... if the house is leaky then unless the boiler is running all day it will be the same issue. As soon as it turns of the house will be cold.

Cab you explain your esb comment? Why would the op need more than standard for a heat pump?

GreeBo

ercork wrote: »

As I understand it heat pumps output about 15kW of heat. If your property is well insulated this is probably plenty heat to keep it at 20 C all day long, or whatever temp you like. However an older, draughtier property would need more heat than this to keep it warm. Gas boilers can produce 30 - 40 kW of heat and would do a better job heating such a place.

agreed, but unless they are running ask the time they won't keep it at that heat either... so then where did all those savings go?

Lumen

I would get new windows and a boiler.

Surely you've learned empirically that windows don't maintain performance indefinitely, so whilst the HP may be fine on day one, what about in 20 years time when the windows are leaky?

Are you going to spend another 20k on windows then?

s7ryf3925pivug

GreeBo wrote: »

agreed, but unless they are running ask the time they won't keep it at that heat either... so then where did all those savings go?

Into my extension, which I might not be able to afford if I put tens of thousands into upgrading my heating.

No-one is saying the heat pump isn't a better option - if I could magic the work in place, be certain it would all work well, and be rich enough that tens of thousands in initial outlay wouldn't make a dent.

Going off on a tangent but I think ventilation is the biggest issue with the insulation of the house. It's not great so we need to open windows a lot, which obviously loses heat. Am looking to get DCV system installed.

GreeBo

Merrick Fancy Symbol wrote: »

Into my extension, which I might not be able to afford if I put tens of thousands into upgrading my heating.

No-one is saying the heat pump isn't a better option - if I could magic the work in place, be certain it would all work well, and be rich enough that tens of thousands in initial outlay wouldn't make a dent.

Going off on a tangent but I think ventilation is the biggest issue with the insulation of the house. It's not great so we need to open windows a lot, which obviously loses heat. Am looking to get DCV system installed.

Will you not be upgrading the windows anyway over the next while?

You don't need tens of thousands to install a heat pump.

Do you have wall vents? It would be strange to have an air leak issue along with a lack of ventilation issue.

s7ryf3925pivug

GreeBo wrote: »

Will you not be upgrading the windows anyway over the next while?

You don't need tens of thousands to install a heat pump.

Do you have wall vents? It would be strange to have an air leak issue along with a lack of ventilation issue.

No plans to upgrade windows. Will probably get seals checked. Working through a big list of high priority jobs for the house. Windows are not on it.

15k for heat pump plus lots more for high efficiency doors and windows and low temperature rads. Heat pumps are good for houses built after 2005. My house was built in the 70s.

I have no idea if there’s an air leak issue. You can hear people the other side of closed windows easily so I think their insulation is bad for one reason or another.

I think there’s a ventilation issue because humidity levels in the house are typically 65%-70% unless all the windows are opened. Think there is only one wall vent apart from the **** fans in the kitchen and bathroom. Otherwise just trickle vents on windows. No wall vent in kitchen despite presence of stove there. I believe that is against regulations. (There is also a wood mantelpiece too close to the stove. We are ditching the stove and bricking up the fireplace.) There’s a ceiling vent in the hall that had a tube in the attic that just led into a patch of the insulation it was lying on - which had gone mouldy from condensation.

There’s a lot of stupid **** that was done with the house tbh.

H.E. Pennypacker

Might be worth getting a thermal imaging & door blower test done. The latter will highlight a lot of potential cheap fixes and give you a better understanding of what you're dealing with. Its a useful way of targetting future spend.

I got quotes for DCV and MHRV ('50s bunglow with reasonable air tightness). As there was very little difference in terms of price, I went for the latter and it transformed the house. Humidity levels have dropped markedly and the house is a more pleasant place to be in. I'm not sure that there's a definable ROI but it was worth every cent.

If you have EWI best to check that it hasn't reduced attic ventilation if it was retrofit and the attic was previously dependent on soffit vents. Not a major deal comfort-wise but may affect the integrity of the roof structure over time.