ASHP or Oil boiler

[tridimnaw]

My partners cousin is renovating a old stone wall house, ive no experience of ASHP but have installed hundreds of oil boilers. Are ASHP a good substitute for oil in this situation? As the insulation wont be as much as a new build??

 

[oz-plumber]

What's the heatload required and what sort of heating do you intend on installing?

Do you intend to have DHW incorporated into the system?

 

[joni os]

My knowledge of ASHPs, is in well insulated new builds. Even in those circumstances the experience has not been gratifying with the COP being least, when heat is needed most.
In one instance, on a development of 250 properties, only that owned by housing association,10%, had ASHP. The remaining 90%, private sale, had gas. Judgement that given choice, what the consumer would choose.
EDF now have a government agreed wholesale price of £89.5 per Mwh for 2023, the current price is £44. Consumers can expect their household tariff to double pro-rata. over the next 8 years. Electricity for heating is not going to be good news.

 

[Dan-HybridHeat]

Keep it simple and stick to oil if you don't know much about them

 

[Sparkgap]

Have just finished a commercial ASHP install of about 100kW in a new build with UFH. A few lessons learned: ASHPs usually quote CoPs etc for certain outside temps, in our case it was 7C. When we challenged the suppliers to give us a setup which would cope with the design conditions (-3C outside, 100kW heat load) the size of the unit went up about 35% and CoP was not fantastic. Check your electric supply: in our case we had to replace a transformer (it was being done anyway but the additional loading meant we didn't have the requested 20% spare capacity) and depending on the rating of the ASHP could mean problems for domestic supplies if you also have electric cooker/shower etc. Don't bother with ASHP for hot water: if you want water temps above 50C you need a two stage ASHP and the CoP sucks.
For an old property even with additional insulation I'd stick with oil.

 

[quality]

I have replaced oil boilers with ASHP many times (more than 100) with very good results. The building fabric and selection of what is installed is far more important than xx Kw unit providing xx heat. ASHP in the proper application are spot on and will knock spots of oil & LPG, but only if specified and the system designed correctly

 

[Worcester]

Designed properly ASHP's work really well in well insulated buildings and with the Governments support, the extra capital install cost is easily recovered.

Sparkgap's post is precisely why you should use an experienced, qualified professional to design and install - same as you would for an oil or gas boiler. What he points out we could have told him before he even started, classic carp designers..

Heatpumps work best with lower flow temperatures. As an example we have just completed an install in a refurbished 250m2 property - original heat load 38kW, new heat load, after refurb 9.8 kW, downstairs ufh, 1st and 2nd floor radiators 4.3 x bigger than oil however due to the much lower heat load, they still aren't large. (designed flow temp 40°).

A heat pump will be cheaper than mains gas, lpg or leccy to run, however with oil at a it's lowest price for 8 years, oil is currently the cheapest form of heating you can install.

Not for long, with the BRIC group massively increasing its energy consumption then the global price will go up as quickly as its come down.

SO, if you have a short term outlook go oil, (5 years)

If your looking to live in the property long term 10-15 years or more, I'd go for heat pump.

On the basis that insulation is ALWAYS cheaper than heat, there is no reason at all why he can't exceed current building regulations insulation levels (loads of our customers do he does need to use the right techniques though if he needs to maintain the breathability of the walls.

More and more consumers are becoming ware of the benefits of a good heat pump installation - ask any of our clients.
Done properly a quality renovation to current insulation levels will always sell more easily and for a higher value than a not so well insulated oil fired property.

So if he's looking for the cheapest conversion, skip on the insulation, shove an oil boiler in and flog the property quick.

If he's looking for a property that he's still enjoying in 15 years, insulate it well and put in a heat pump, over a 10 year period, both will work out the same cost.

 

[Sparkgap]

Designed properly ASHP's work really well in well insulated buildings and with the Governments support, the extra capital install cost is easily recovered.

Sparkgap's post is precisely why you should use an experienced, qualified professional to design and install - same as you would for an oil or gas boiler. What he points out we could have told him before he even started, classic carp designers..

Quite agree. This one came from a well-known national firm of mechanical consultants and when the information about the system came from the manufacturers that was when we queried the temperatures.

Heatpumps work best with lower flow temperatures. As an example we have just completed an install in a refurbished 250m2 property - original heat load 38kW, new heat load, after refurb 9.8 kW, downstairs ufh, 1st and 2nd floor radiators 4.3 x bigger than oil however due to the much lower heat load, they still aren't large. (designed flow temp 40°).

A heat pump will be cheaper than mains gas, lpg or leccy to run, however with oil at a it's lowest price for 8 years, oil is currently the cheapest form of heating you can install.

Obviously if you can improve the insulation to reduce the fabric heat losses then even better! Eventually though you get to the stage where increasing the insulation produces minimal savings in heating because most of the load is by now taken up by vent losses. That's where MVHR comes in.
I also approve of increasing rad sizes to enable lower flow temperatures, which would also work for condensing oil or gas boilers.
As for heatpumps being cheaper, current figures have Kerosene cheapest at 3.51p/kWh, mains gas at 4.17p, gas oil 5.01p and ASHP 5.68p. A lot depends on CoP and GSHP are better at 4.38p due to their higher efficiencies.