ASHP vs LPG - Round 2

[SteamyTea]

10 minutes ago, epsilonGreedy said:

GridWatch is just a weekend side project run by an enterprising computer programmer

You know there are 2 sites?

The main one gets the data from Elexon, if you hunt around there, there are some notes about what is metered and what isn't.

Without looking back up the posts, do your numbers match with the link you just posted?

13 hours ago, epsilonGreedy said:

Peak wind output in 2021 was 14GW

Average wind output was 5.6GW

Ah, they do, needed to scroll down a bit more.

[epsilonGreedy]

3 hours ago, SteamyTea said:

 

Ah, they do, needed to scroll down a bit more.

 

 

You need a bigger phone screen.

 

Today was a record peak for UK wind power, must be the result of Triton Knoll coming online. I regularly drive over its feed into the national grid and it clonks my suspension.

 

Enjoy today while it lasts, how many turbines will tumble tomorrow?

[PeterW]

12 hours ago, Dave Jones said:

 

bit disingenuous. 

 

You are leaving out the tanks, pipework and room to store it all for a heat pump.

 

Realistically no one will supply and fit an ASHP, tanks, pipes etc for £2300. More like £10k.

 

None of which is necessary with a combi.

Not really - you need the same with DHW setup on either a system boiler or an ASHP so irrelevant to include. Also neither I or the OP talked about comparing a combi with an ASHP, and tbh you’ve got an issue with flow rates anyway on combi’s so mains pressure is out of the window. 

[PeterW]

21 hours ago, redtop said:

Nit sure thats comparing like for like. Quick Google and gas boilers from 800 quid to 1200 ish. 9kw ashp from 2300 up to 4500. And our GSR charges around 250 a day, is brilliant but would have to learn how to fit an ASHP. 

A plumber that can read can fit an ASHP. They are simple.

 

I wouldn’t fit an £800 gas boiler which when you factor in flues etc will be up toward the £1000 anyway. 

 

And a comparison of a combi that will run a single shower to an ASHP and UVC set up that will run multiple mains pressure outlets is chalk and cheese. 
 

 

[JohnMo]

5 minutes ago, PeterW said:

 

And a comparison of a combi that will run a single shower to an ASHP and UVC set up that will run multiple mains pressure outlets is chalk and cheese. 
 

 

Not sure I agree fully  I have an Atag A325ECX (combi) and had three showers running the other day.  The only modification to the standard configuration are

1.  Flow restrictor not installed

2.  I have PV with immersion diverter, so have a thermal store, upstream and cold water passes through the DHW coil on its way to the combi. So will get some preheat (read point 4)

3.  UFH is connected to thermal store.

4. Combi heats the thermal store to 40 degs (no real PV generated in winter).  So DHW gets preheated to about 25 degs in winter.

 

 

 

[PeterW]

5 minutes ago, JohnMo said:

The only modification to the standard configuration

I wouldn’t call those minor !!! You’re running a 32kW gas combi without its flow restrictors, and you’re only heating the water by 17°C… that isn’t exactly stretching it to do 33°C uplift on standard flow (which from memory is about 21l/min max on those) so without the preheat you’re not going to get 3 decent showers running. 
 

And apologies, it was the comment in this post about combi and single shower I was referring to. 
 

 

I have no issues with a combi in the right place but if you want flow rates then you’re into domino setups and preheater tanks which can easily be replaced by a decent large UVC and a lot less hassle. 

[scottishjohn]

very interesting thread 

 I have also been considering which way to go when i eventually get started 

and although I have ASHP in current house   and was considering this as first choice 

 

maybe that is wrong now 

 

but i would not be fitting a combi ,but a system boiler be it lpg or oil and a UVC as space will not be a problem

 

 If I go PV as well then alot of that can be used to keep UVC hot as I did with my solar water panels  in this house  and of course save some elec  as well

 that tank had a solar coil and was also had underfloor coil and third coil at top for hot water supply- any heat made  by what ever means went to the UVC and sent to where ever required

 this time If go that way it would be a taller tank to get even better stratification 

 

 and that brings on the next thoughts -how far off are we from pv panels +battery prices being a viable choice -if elec grid connection is going to be 15 -20K

diesel/heating oil generator ,for some winter top up  of batteries as well

 

all thoughts are welcome 

[Nickfromwales]

17 minutes ago, scottishjohn said:

that tank had a solar coil and was also had underfloor coil and third coil at top for hot water supply- any heat made  by what ever means went to the UVC and sent to where ever required

That was a thermal store ( TS ) not an unvented hot water cylinder ( UVC ).   

[scottishjohn]

5 minutes ago, Nickfromwales said:

That was a thermal store ( TS ) not an unvented hot water cylinder ( UVC ).   

ok wrong terminology 

 sorry

[SteamyTea]

18 minutes ago, scottishjohn said:

all thoughts are welcome 

Design your electrical system as if it is an off grid place, then you can plug in either a generator or a battery system.

The PV system may as well be an off grid system to start with, either pump into so thermal storage (water or rocks) and a small battery for lighting.

Cooking becomes the harder part.  Even a small induction hob is going to need 2 kW and an oven 1.5 kW.  So maybe bottled gas for those until PV/battery prices make it viable. Just stick in the wiring and swapping them over is easy.

Just keep it all simple, low capacity (so don't have 50 downlighters around the place) and flexible with radial circuits.

[SBMS]

Does a PV array to give a return on investment for offsetting ASHP electricity costs? A large proportion of running time will be when it’s dark so probably only a few hours offset with a PV array. Could use batteries but again, how many years before payback? I’ve heard that PV array costs have gone up with latest chip supply issues as well. It’s something I discounted when researching as I couldn’t make the maths work. But if electricity costs keep increasing maybe it makes more sense?

[scottishjohn]

this is the idea for a thermal store 

https://www.youtube.com/watch?v=fKb-lKuLlpQ

swop solar thermal fro extra input like oil or gas and top postion where they have the oil or gas burner have the pv heater 

any commments

[Nickfromwales]

2 hours ago, scottishjohn said:

ok wrong terminology 

 sorry

Not wrong terminology, completely different bit of kit altogether. Just don’t want you basing new / fresh assumptions on the wrong bit of kit  

Edited February 18, 2022 by Nickfromwales

[redtop]

12 hours ago, PeterW said:

A plumber that can read can fit an ASHP. They are simple.

 

I wouldn’t fit an £800 gas boiler which when you factor in flues etc will be up toward the £1000 anyway. 

 

And a comparison of a combi that will run a single shower to an ASHP and UVC set up that will run multiple mains pressure outlets is chalk and cheese. 
 

 

Its not really chalk and cheese. In practice our waterfall shower is plenty powerful enough, I wouldnt want more water coming out of it. And yes, run multiple showers and Pressure drops but we have a high flow combi so it should cope, but tbh I wouldnt know as we have never used more than 1 shower or bath at a time. But also never ever run out of hot water. So chalk and cheese it isn't, pros and cons yes depending on what is important to you. Neither more hot water pressure or the ability to run multiple hot water outlets at same time matters to us. I would add we have used the manifold system for hot and cold, so a separate pipe for every outlet with showers prioritised, so turning on a hot tap while having a shower makes no difference. And I know ASHP are simple, but there are a lot of plumbers that have never fitted them and when its a learning curve, it costs.

[joe90]

1 hour ago, redtop said:

And I know ASHP are simple, but there are a lot of plumbers that have never fitted them and when its a learning curve, it costs.

Well I am not even a plumber and I fitted mine (and I can read) , apart from a recent problem (which was my fault) it works fine.

[redtop]

6 hours ago, joe90 said:

Well I am not even a plumber and I fitted mine (and I can read) , apart from a recent problem (which was my fault) it works fine.

I know they are easy to fit. But how much time did you spend reading how to do it? In any event fitting a gas boiler and ASHP are both easy, I think ours was fitted and tested in half a day

[Roger440]

20 hours ago, scottishjohn said:

very interesting thread 

 I have also been considering which way to go when i eventually get started 

and although I have ASHP in current house   and was considering this as first choice 

 

maybe that is wrong now 

 

but i would not be fitting a combi ,but a system boiler be it lpg or oil and a UVC as space will not be a problem

 

 If I go PV as well then alot of that can be used to keep UVC hot as I did with my solar water panels  in this house  and of course save some elec  as well

 that tank had a solar coil and was also had underfloor coil and third coil at top for hot water supply- any heat made  by what ever means went to the UVC and sent to where ever required

 this time If go that way it would be a taller tank to get even better stratification 

 

 and that brings on the next thoughts -how far off are we from pv panels +battery prices being a viable choice -if elec grid connection is going to be 15 -20K

diesel/heating oil generator ,for some winter top up  of batteries as well

 

all thoughts are welcome 

 

Just today i got a ball park cost for a turn key off grid system. Enough for a house and a workshop. £40K + VAT. That included everything required except installation. No user input apart from keeping fuel in the tank.

 

What i found interesting was although a significant capital cost, was that that the cost per KWH was very low. In their best example, 9p per kwh. Ok, its PR and best case, but given current prices, and the near certainty they can only go one way, in your position may be worthy of consideration. Especially if its going to cost £15-20k for a grid connection. Who will then charge you 30p per Kwh for ever + price increases..

 

They quoted me the 15000 version, which is overkill for a house, so would expect a slightly lower cost.  https://www.energy-solutions.co.uk/guides/off-grid-guide.pdf

You just have to get past a diesel genset being part of the solution......................

[scottishjohn]

On 18/02/2022 at 18:12, Roger440 said:

Just today i got a ball park cost for a turn key off grid system. Enough for a house and a workshop. £40K + VAT. That included everything required except installation. No user input apart from keeping fuel in the tank.

 

What i found interesting was although a significant capital cost, was that that the cost per KWH was very low. In their best example, 9p per kwh. Ok, its PR and best case, but given current prices, and the near certainty they can only go one way, in your position may be worthy of consideration. Especially if its going to cost £15-20k for a grid connection. Who will then charge you 30p per Kwh for ever + price increases..

 

They quoted me the 15000 version, which is overkill for a house, so would expect a slightly lower cost.  https://www.energy-solutions.co.uk/guides/off-grid-guide.pdf

You just have to get past a diesel genset being part of the solution......................

diesel gen  and batteries + solar pv +generator?

 how big was the pv array + storage 

lead acid  batteries?

Edited February 19, 2022 by scottishjohn

[Roger440]

20 hours ago, scottishjohn said:

diesel gen  and batteries + solar pv +generator?

 how big was the pv array + storage 

lead acid  batteries?

 

Yes, all of that. Update. Array was 6.8Kw. But you can have a bigger one if you want

 

Lithium batteries. 30kwh

 

Decent perkins genset too ui f i remember correctly?.

 

He quoted the 15000i on this page but with a 6.8kw array. Mainly as i would have a releatively power hungry workshop. For a big house the 10000i is normally enough. https://www.energy-solutions.co.uk/products/easygrid

 

Just need to add waste heat recovery from genset exhaust for the best possible result.

 

The guy was really helpful. As he said, its like being connected to the grid from an end user perspective.

Edited February 20, 2022 by Roger440

[billt]

On 18/02/2022 at 18:12, Roger440 said:

 

Just today i got a ball park cost for a turn key off grid system. Enough for a house and a workshop. £40K + VAT. That included everything required except installation. No user input apart from keeping fuel in the tank.

 

What i found interesting was although a significant capital cost, was that that the cost per KWH was very low. In their best example, 9p per kwh. Ok, its PR and best case, but given current prices, and the near certainty they can only go one way, in your position may be worthy of consideration. Especially if its going to cost £15-20k for a grid connection. Who will then charge you 30p per Kwh for ever + price increases..

 

They quoted me the 15000 version, which is overkill for a house, so would expect a slightly lower cost.  https://www.energy-solutions.co.uk/guides/off-grid-guide.pdf

You just have to get past a diesel genset being part of the solution......................

 

I think that you've misinterpreted the cost per kWh. The 9p per kWh seems to be based on the generator running costs; the generator can be run at full load and hence maximum efficiency if charging a battery bank intermittently, with assistance from PV. They are not accounting for the capital cost, which will push the cost per kWhr up nearer 75p.

 

Because I'm stupid and like playing with toys, I have an (in effect) off grid system. It has 14.7kW of panels, 13kW of inverters feeding a Sunny Island 8.0 inverter/charger with about 19kWh worth of LiFEPO4 batteries. It cost about £32,000, including 20% VAT (would be quite a lot cheaper now, as costs have dropped a lot since I started buying bits) and generated about 5,000 kWh over the last 12 months. It should generate a bit more now it is completely commissioned and I've got some extra load in the summer. If you assume a 10 year life, that gives a unit cost of £0.65. If you were lucky and got 20 years out of it the cost drops to £0.33, however that doesn't include fuel for the generator in the 3 months when PV is inadequate.

[Roger440]

28 minutes ago, billt said:

 

I think that you've misinterpreted the cost per kWh. The 9p per kWh seems to be based on the generator running costs; the generator can be run at full load and hence maximum efficiency if charging a battery bank intermittently, with assistance from PV. They are not accounting for the capital cost, which will push the cost per kWhr up nearer 75p.

 

Because I'm stupid and like playing with toys, I have an (in effect) off grid system. It has 14.7kW of panels, 13kW of inverters feeding a Sunny Island 8.0 inverter/charger with about 19kWh worth of LiFEPO4 batteries. It cost about £32,000, including 20% VAT (would be quite a lot cheaper now, as costs have dropped a lot since I started buying bits) and generated about 5,000 kWh over the last 12 months. It should generate a bit more now it is completely commissioned and I've got some extra load in the summer. If you assume a 10 year life, that gives a unit cost of £0.65. If you were lucky and got 20 years out of it the cost drops to £0.33, however that doesn't include fuel for the generator in the 3 months when PV is inadequate.

 

I know it doesnt include the capital cost. Rather depends on over what period you want to amortise them too.

 

For someone like scottishjohn where the DNO want £20k to connect anyway, then its starts to look more sensible. I cant imagine it would ever make sense if you actually have a grid connection.

 

I looked at it as i was looking at a property with no connection and no realistic praability of one. Certainly not for £20k!

 

I assume you set up feeds into the grid too? How long do you anticipate your batteries lasting?

[scottishjohn]

1 hour ago, billt said:

 

I think that you've misinterpreted the cost per kWh. The 9p per kWh seems to be based on the generator running costs; the generator can be run at full load and hence maximum efficiency if charging a battery bank intermittently, with assistance from PV. They are not accounting for the capital cost, which will push the cost per kWhr up nearer 75p.

 

Because I'm stupid and like playing with toys, I have an (in effect) off grid system. It has 14.7kW of panels, 13kW of inverters feeding a Sunny Island 8.0 inverter/charger with about 19kWh worth of LiFEPO4 batteries. It cost about £32,000, including 20% VAT (would be quite a lot cheaper now, as costs have dropped a lot since I started buying bits) and generated about 5,000 kWh over the last 12 months. It should generate a bit more now it is completely commissioned and I've got some extra load in the summer. If you assume a 10 year life, that gives a unit cost of £0.65. If you were lucky and got 20 years out of it the cost drops to £0.33, however that doesn't include fuel for the generator in the 3 months when PV is inadequate.

that makes more sense=other wise lots would be doing it

[billt]

14 hours ago, Roger440 said:

For someone like scottishjohn where the DNO want £20k to connect anyway, then its starts to look more sensible. I cant imagine it would ever make sense if you actually have a grid connection.

 

I looked at it as i was looking at a property with no connection and no realistic praability of one. Certainly not for £20k!

 

I assume you set up feeds into the grid too? How long do you anticipate your batteries lasting?

 

Yes, I' definitely a good idea if the grid connection costs are high.

 

No, it doesn't feed into the grid. It's a DIY non MCS install and the SI 8.0 isn't approved for grid connection.

 

Battery life - how long is a piece of string? The makers claim 7000 cycles at 70% DOD. That works out at 19 years at a cycle a day, however they tend not to do a full discharge every day so the batteries aren't being driven very hard and who knows how credible the makers life expectancy is.

 

I thought of another cost, loss of interest. At a pessimistic 2.5% that adds 16p per unit.

[Roger440]

8 minutes ago, billt said:

 

Yes, I' definitely a good idea if the grid connection costs are high.

 

No, it doesn't feed into the grid. It's a DIY non MCS install and the SI 8.0 isn't approved for grid connection.

 

Battery life - how long is a piece of string? The makers claim 7000 cycles at 70% DOD. That works out at 19 years at a cycle a day, however they tend not to do a full discharge every day so the batteries aren't being driven very hard and who knows how credible the makers life expectancy is.

 

I thought of another cost, loss of interest. At a pessimistic 2.5% that adds 16p per unit.

 

Thanks. Interesting setup.

 

Ref the interest, doesnt really apply, as if i didnt spend that money, it would only be because im not buying that particular property. Buying an equivalent property with a connection, would, inevitably, cost more.

 

[Ferdinand]

On 17/02/2022 at 08:32, epsilonGreedy said:

 

There is a 5 to 10 year gap between reality and your happy clappy tree hugger view of the world. 

 

If you are choosing to indulge in unnecessary personalised insults, I'm not interested.

 

Don't bother replying to me; you are now on ignore.