Octopus Heat Pumps

Meatballs

Perfect is the enemy of good 

Screwdriva

Netexporter said:

Even a 100% efficient boiler is putting a lot of CO2 into the atmosphere. There is embedded carbon in the making of the boiler, too. The greener the electricity supply becomes the dirtier a boiler looks.

No arguments from me about either of those points. I would imagine the CO2 for manufacturing a boiler would be substantially lower than a heat pump + ~ 13 kW of batteries, but without numbers, it's all speculation.  

Personally, I would never advocate fitting a boiler over a heat pump in the right property in 2023. That said, an air source heat pump isn't the universal magic bullet for all our emissions related woes either. From my own experience, rural properties  may benefit more from a ground source solution the same way a flat may benefit from an air to air solution, both of which deliver higher SCOPs consistently throughout colder months, and are viable alternatives if the stars align. 

Thanks all for the insights! I've attached the latest average UK SCOP #s for heat pumps. Looks like parity against a modern gas boiler would need to be a SCOP of 3.5.

1961Nick

Screwdriva said:

Netexporter said:

Even a 100% efficient boiler is putting a lot of CO2 into the atmosphere. There is embedded carbon in the making of the boiler, too. The greener the electricity supply becomes the dirtier a boiler looks.

No arguments from me about either of those points. I would imagine the CO2 for manufacturing a boiler would be substantially lower than a heat pump + ~ 13 kW of batteries, but without numbers, it's all speculation.  

Personally, I would never advocate fitting a boiler over a heat pump in the right property in 2023. That said, an air source heat pump isn't the universal magic bullet for all our emissions related woes either. From my own experience, rural properties  may benefit more from a ground source solution the same way a flat may benefit from an air to air solution, both of which deliver higher SCOPs consistently throughout colder months, and are viable alternatives if the stars align. 

Thanks all for the insights!

My solution was to fit 2 air/air splits downstairs & a ducted system serving 3 rooms upstairs to supplement rather than replace the gas boiler. I'm getting SCOPs of 5.4 & 5.1 on the downstairs units & around 3.5 on the upstairs ducted system. 60% of the house is now heated/cooled by heat pumps but it's probably 95% of the space we actually use. The rolling average gas consumption has reduced from 28,800kWh pa to just under 10,000kWh pa. Electricity consumption has risen by 4500wWh over that period but 2/3 of that is attributable to getting the Tesla.

Over 90% of the electricity we import is 7.5p/kWh Intelligent Octopus.

michaels

1961Nick said:

Screwdriva said:

Netexporter said:

Even a 100% efficient boiler is putting a lot of CO2 into the atmosphere. There is embedded carbon in the making of the boiler, too. The greener the electricity supply becomes the dirtier a boiler looks.

No arguments from me about either of those points. I would imagine the CO2 for manufacturing a boiler would be substantially lower than a heat pump + ~ 13 kW of batteries, but without numbers, it's all speculation.  

Personally, I would never advocate fitting a boiler over a heat pump in the right property in 2023. That said, an air source heat pump isn't the universal magic bullet for all our emissions related woes either. From my own experience, rural properties  may benefit more from a ground source solution the same way a flat may benefit from an air to air solution, both of which deliver higher SCOPs consistently throughout colder months, and are viable alternatives if the stars align. 

Thanks all for the insights!

My solution was to fit 2 air/air splits downstairs & a ducted system serving 3 rooms upstairs to supplement rather than replace the gas boiler. I'm getting SCOPs of 5.4 & 5.1 on the downstairs units & around 3.5 on the upstairs ducted system. 60% of the house is now heated/cooled by heat pumps but it's probably 95% of the space we actually use. The rolling average gas consumption has reduced from 28,800kWh pa to just under 10,000kWh pa. Electricity consumption has risen by 4500wWh over that period but 2/3 of that is attributable to getting the Tesla.

Over 90% of the electricity we import is 7.5p/kWh Intelligent Octopus.

Sadly the powers that be are only willing to support wet system gas replacement

Out of interest, what was the ballpark cost?

1961Nick

michaels said:

1961Nick said:

Screwdriva said:

Netexporter said:

Even a 100% efficient boiler is putting a lot of CO2 into the atmosphere. There is embedded carbon in the making of the boiler, too. The greener the electricity supply becomes the dirtier a boiler looks.

No arguments from me about either of those points. I would imagine the CO2 for manufacturing a boiler would be substantially lower than a heat pump + ~ 13 kW of batteries, but without numbers, it's all speculation.  

Personally, I would never advocate fitting a boiler over a heat pump in the right property in 2023. That said, an air source heat pump isn't the universal magic bullet for all our emissions related woes either. From my own experience, rural properties  may benefit more from a ground source solution the same way a flat may benefit from an air to air solution, both of which deliver higher SCOPs consistently throughout colder months, and are viable alternatives if the stars align. 

Thanks all for the insights!

My solution was to fit 2 air/air splits downstairs & a ducted system serving 3 rooms upstairs to supplement rather than replace the gas boiler. I'm getting SCOPs of 5.4 & 5.1 on the downstairs units & around 3.5 on the upstairs ducted system. 60% of the house is now heated/cooled by heat pumps but it's probably 95% of the space we actually use. The rolling average gas consumption has reduced from 28,800kWh pa to just under 10,000kWh pa. Electricity consumption has risen by 4500wWh over that period but 2/3 of that is attributable to getting the Tesla.

Over 90% of the electricity we import is 7.5p/kWh Intelligent Octopus.

Sadly the powers that be are only willing to support wet system gas replacement

Out of interest, what was the ballpark cost?

The short answer is higher than it needed to be because we paid a hefty 'aesthetic' premium for the 2 downstairs splits - those 2 cost £4400 (3.5kWh & 5.4kWh WiFi enabled). The upstairs ducted unit's cost will be around £3600 when it's finally serving all 3 rooms. Installation was time consuming with all the pipework run through the cavity wall & a new 45m 4mm cable run from the CU to the outdoor units. Upstairs was ducted because we preferred minimalist ceiling grills rather than bulky wall or floor mounted splits. The master bedroom was also awkward because of the distance from the outdoor unit - having the indoor unit in the loft with ducting going the rest of the way kept the pipe run to less than 20m & meant we could add 2 more rooms as a bonus. The SCOP isn't great at 3.5 (ish) but still better than most air/water heat pumps.

Edit: 
I should have mentioned that the relatively poor SCOP of the upstairs ducted system is largely offset by the fact that it'll mainly be run during the 23.30 - 05.30 Intelligent Octopus off peak period @ 7.5/kWh... just over 2p/kWh of heat.

michaels

Do you need planning permission if you have more than one outdoor unit?

mickyduck55

michaels said:

Do you need planning permission if you have more than one outdoor unit?

I needed planning permission for my new ASHP (air to water) as I already had an air / air split system.  PITA you would have thought I was building a 100 house estate not just sticking a metal box by my garage

shinytop

michaels said:

Do you need planning permission if you have more than one outdoor unit?

Yes and you also need it if you only have one and ever use it for cooling.

1961Nick

shinytop said:

michaels said:

Do you need planning permission if you have more than one outdoor unit?

Yes and you also need it if you only have one and ever use it for cooling.

I wonder what percentage of air/air splits actually have planning permission? Substantially below 1% would be my guess.

DougMLancs

OVO have partnered with Heat Geek and launched a 15p/kWh tariff to join the ASHP party. Starting from £500 (although how many will start at that will remain to be seen). https://www.elementaldigital.co.uk/ovo-cuts-heat-pump-running-costs-and-partners-with-heat-geek/