Two possible heat p...
 
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Two possible heat pump routes - how to evaluate them?

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(@johnmo)
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Think it also assumes you would actually want to switch to OVO, I voted with my feet and moved away to Octopus. My direct debit got bigger the longer I stayed there even though I was in huge credit mid winter. With Octopus my direct debit is slowly coming down, and is at a reasonable place.


   
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(@ivanopinion)
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Posted by: @johnmo
Think it also assumes you would actually want to switch to OVO, I voted with my feet and moved away to Octopus. My direct debit got bigger the longer I stayed there even though I was in huge credit mid winter. With Octopus my direct debit is slowly coming down, and is at a reasonable place.
I found Octopus were just as bad on that. I lost patience and simply told them to bill me for what I use each month. It does mean that budgeting is a bit harder, but that's better than lending my money to energy companies.

 


   
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Majordennisbloodnok
(@majordennisbloodnok)
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Posted by: @ivanopinion

Posted by: @johnmo
Think it also assumes you would actually want to switch to OVO, I voted with my feet and moved away to Octopus. My direct debit got bigger the longer I stayed there even though I was in huge credit mid winter. With Octopus my direct debit is slowly coming down, and is at a reasonable place.
I found Octopus were just as bad on that. I lost patience and simply told them to bill me for what I use each month. It does mean that budgeting is a bit harder, but that's better than lending my money to energy companies. 

We use Octopus and so does my mother. In both cases, we've found that Octopus' "recommended" amount is a slight overestimate, but that since it's easy to set a monthly amount we just make use of that. It becomes far more like a standing order than a direct debit and we are still able to overpay in the summer to ensure the winter bills aren't a short-term problem.

It's particularly important for us, though, since the combination of ASHP and solar PV polarises the bills. It's a bit like

April - net zero bill

May - small rebate

June - rebate

July - rebate

August - rebate

September - small rebate

October - small cost

November - BIG BILL

December - BIG BILL

January - BIG BILL

February - BIG BILL

March - small cost

As a result, even though the overall yearly cost is far lower than when we were using an oil boiler the monthly ups and downs can be quite unnerving and the ability to even out over the year is definitely an important tactic.

 

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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(@lucia)
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Topic starter  
IMG 1756
IMG 1755
IMG 1753
IMG 1757

I have found a new toy which is useful if taken as a general indication

I have no idea how accurate it is but it comes (via open energy) from a Daikin installer portal. For me, I was interested in the power demands. Look at those images where I was playing with LWT and let me know what you think.

Large pinch of salt needed or what?


   
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(@lucia)
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I've got Heat Pumps rising this week - energy efficiency things planned 9 months ago have landed all in the same week - EPC, GBIS assessment and both the British Gas survey and the Octopus survey result. 

The British gas survey was as thorough as Octopus and done by a tech guy not a sales person. The difference is I've now seen my cavity wall insulation gaps via borescope so I told him. MCS survey software only allows insulated/not insulated so he asked me to choose.... We ended up trying both. 

It made no difference to heat pump sizing only to the radiators. BG design for a flow temp of 45º. Either way my recommended heat pump size was.... drum roll Daikin 6kw. Exactly what my calculations have arrived at. 

Meanwhile, Octopus came back to me with a system design spec and a Daikin 4kw heat pump. I have told them I think it's too small and I'm peeved at the 50º design temp. 

I have written a list of my criticisms making it clear that I'm criticising the limitations of MCS software not any people (who have all been great so far). I've written to the GBIS department at Octopus asking them to please share the report with their colleagues in the Heat Pump dept. 

Octopus think 4kw will be fine but they do seem to be considering my comments and others on the team will look at my points and (hopefully) the GBIS report later on. A result for me will be 45º design temp & 6kw heat pump. I suspect I may get the former but not the latter. We'll see. But at least my objections are on record. 

BG are including more radiator changes, a Gledhill 180ltr water tank but charging me £1000 more and I think I will have to pay for the gas capping and meter removal. 

It's swings and roundabouts time....

Meanwhile, Daikin owners please have a look at the images in my last post and let us know if the results match your temperature and energy use ratios? 


   
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(@bontwoody)
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@lucia If you are on an octopus tariff (Not installation) they are still removing and capping the gas meter free of charge. I had mine done several months back.

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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(@ivanopinion)
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@lucia Are BG specifying a buffer or low loss header? I'm curious whether Brendon's influence has had an effect.


   
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(@lucia)
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@ivanopinion

Lol... yes, they are insisting on a buffer. 

I wasn't going to push back on that because I knew it was pointless although I did say that I'd heard a lot of criticism of buffers. 

Octopus are insisting on a volumiser. 


   
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(@johnmo)
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Posted by: @lucia

yes, they are insisting on a buffer. 

Octopus are insisting on a volumiser.

Are you zoning the heating system or just a a fully open single zone?


   
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(@lucia)
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@johnmo Oh, strictly open loop. No zoning and all rads no under floor heating.


   
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Jancold
(@jancold)
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Well BG are coming to see me tomorrow, If he insists on a buffer maybe I'll ask to be referred to Brenden 🤔 


   
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(@lucia)
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@bontwoody Yes, that's another thing to weigh up in the swings and roundabouts dept. British Gas charge for it. 

I did tell the British gas guy I thought it bizarre that they let Octopus beat them on that when they are supposed to be 'THE' gas company. He just said it's a different company under the BG umbrella .... (probably what they euphemistically call 'tax efficiency') 🙄


   
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