Benefits of a thermal store?

[dpmiller]

Dunno where you get your oil boilers from, Nick...

[scottishjohn]

the suggestion to me today from sunamp --as i have not started new build 

ASHP -hightemp type  65c ,but only if  you can get off peak cheap electric(lower COP from high temp type)--no thermal store -run UFH from ASHP

now if no night time cheap electric then use normal low temp ASHP 40-45 and then a sunamp with a built in immersion booster element --to lift it over the threshold for phase change.

Of course if you going PV as well then you can use excess from that to charge up the unit..

they say the cost of a sunamp to replace a  210litre thermal store is the same .

i didn,t go into it any more as its next year before I will need it,and things may change  

 

 

[Nickfromwales]

12 minutes ago, dpmiller said:

Dunno where you get your oil boilers from, Nick...

Same place i always do. Add flues, fire valves, oil lines, watchmans, etc and up she goes. 

I've been doing it long enough to know, plus I'm not quoting DIY, I'm quoting what you'll pay to have it installed through a 3rd party. Glass half full when its DIY vs fag packet, and glass half empty when you get the costs with all of the peripherals  

[Nickfromwales]

A cheap price here

[Declan52]

Is it not more a question of comparing the thermal store and the  sun amp.  The price of the heat pump and all the bits that go with it will be not much different than an oil boiler and its extras(2nd official tax paying job was programing the oil watchman)  .  We  are  spoilt here as we have both grant and warm flow made here plus a few oil tank manufacturers, Kingspan and harelquin so get better prices than you mainland folk.  

So it's just comparing the  thermal store and sun amp.  The sunamp will be higher up front cost and could be depending on your demand you might need 2 units. But long term if you factor in the costs of oil to run your boiler,  with the ever fluctuating price of oil plus service costs, the  heating of your thermal store and factor in heat loss and compare this with the  c.o.p of your heat pump charging the sunamp then the  sunamp should come out on top.  

Then you also have the risk of oil leaks which can destroy a house. 

If I went completely mad in the head and done another build using a sunamp would be  high on my list but  and it's a big but I'm not sure how much knowledge there is here but @Alphonsox put a couple in his house so somebody here does them.  Maybe he could give details of who done his. 

[Ricco]

The chat about ASHP and sunamp is interesting.

I had originally looked at an ASHP but was convinced that unless putting PV on the house the cost of running it would be higher than buying oil needed to run an oil boiler. PV in my mind is out of the question as in NI there is no renewable incentive so the payback time is much longer and it is more capital outlay that I could do without.

 

Can anyone give an indication on running costs without PV?

 

Also, with the heat pump having to charge the sunamp will the c.o.p. reduction not cause it to become massively inefficient and expensive as you demand higher output temperatures from it?

[PeterW]

The question becomes whether using a Sunamp direct on E7 (as per @TerryE) is as efficient as the cost of the additional components needed to use the ASHP to provide the heat to it. 

 

ASHP at 35c is pretty much perfect to provide the heat required for a slab - isolating the two also means you’re not having to run it through the summer to heat the DHW and can leave in cooling mode if needed for the floor. 

[andy]

Interesting, so I could do ASHP direct to multizone slab and PV/direct elec for DHW Sunamp might be best approach for me too.

[Guest Alphonsox]

10 hours ago, Declan52 said:

If I went completely mad in the head and done another build using a sunamp would be  high on my list but  and it's a big but I'm not sure how much knowledge there is here but @Alphonsox put a couple in his house so somebody here does them.  Maybe he could give details of who done his. 

 

We were early adopters with the first install on this side of the water. Our Sunamps only provide DHW and are so the system design was simple and Sunamp were happy for us to install using local plumbers for the wet bits and me doing the electrical connection. Sunamp have moved on considerably since then with many more options to choose from.

[Stones]

There are many ways to skin this particular cat.  I did a cost comparison of ASHP vs direct electric vs oil vs LPG, all with and without solar PV.  I spent a lot of time looking into Sunamp (PVs) as they were then, and had long conversations with them persuading them to consider the concept of extension boxes to increase capacity, but in the end, for our house, and what we needed, an ASHP and UVC was easier, cheaper to buy and cheaper to run, even after accepting the lower COP / higher cost of providing DHW using an ASHP.  The cost per kWh of DHW (inc all losses) delivered to the tap is significantly less than I would pay per kWh for E7 electric.  Heating is cheap as chips.

 

I bought a Mitsubishi Ecodan and a 300L preplumb cylinder.  UFH is fed directly from the ASHP (no buffer - no need!) and we have not had any issues with running out of DHW, despite the sometimes heavy consumption. 

 

Previous cost comparisons that I have done indicate that when your heating requirement is 2500 kWh or less, and DHW requirement 2500 kWh or less, then direct electric is the cheapest and easiest solution.  After that other technologies come into contention and it is a case of trading off positives and negatives of each. 

 

For GSHP, although they have better COP than ASHPs, they can have higher running costs when heating demand is low (5000 kWh or less) due to the increased costs of running circulation pumps and replacing antifreeze.

 

I've detailed everything in my blog if you want to read more.

[TerryE]

14 hours ago, PeterW said:

The question becomes whether using a Sunamp direct on E7 (as per @TerryE) is as efficient as the cost of the additional components needed to use the ASHP to provide the heat to it. 

 

ASHP at 35c is pretty much perfect to provide the heat required for a slab - isolating the two also means you’re not having to run it through the summer to heat the DHW and can leave in cooling mode if needed for the floor. 

 

Jan and I have 2×SunAmps and no buffer preheat.  We are still debating this ASHP or no ASHP issue and it is an ambivalent debate between us because we keep to be swapping positions as well as usually agreeing.  Yes using E7 is more expensive than a HP but then again I don't have the installation and amortisation costs of the ASHP solution.   For us an ASHP only makes economic sense, if I buy one at a sensible discount price and do the install and any routine / annual maintenance myself, because amortising these costs for a turnkey install will wipe out any savings benefits. 

 

I would be interested in what the system installation costs are but if we assume a 10-year life , say,  for an ASHP at a £5K installed system cost and a £200 p.a. annual maintenance -- that's £700 a year.  This still has a (typically peak rate) electricity cost compared to my 3× higher and mostly E7 electricity costs.  But this maintenance element is about what my Willis heater's running costs are for the year anyway.  Hence, I will do as Jeremy and other members here and pick up a reasonable one on eBay or equiv and do the install myself -- that is if Jan and I decide to go down this route.

 

This being said, as Peter says, I feel that there is a lot of merit in running the ASHP at a low temperature (low 30s °C).  There is a separate argument as to whether you can take advantage of a buffer tank to pre-heat the DHW feed to the SunAmp, effectively doubling the capacity, but this is going to require extra valves, PHEs, etc.

 

I think that @Stones has picked up the essence of the trade-off debate: there are tipping points for the optimum solution.

 

Edited November 22, 2018 by TerryE

[joe90]

Now that I have my ASHP going  ?I am really pleased with it, running costs are yet to be seen but I can compare them to the costs for

 the last two months running immersions for  heating (in the buffer tank) and DHW tank. I may consider E7 or E10 to add to the COP that I get. @TerryE where did you get £200 annual maintenance from, as I understand it , it’s like an MVHR in that a visual inspection of the filter/fins is required (DIY) and the pressure tank inspection that’s required, can’t imagine that’s £200 a time? My ASHP (brank new still on its pallet and still shrink wrapped but no gaurentee)  was £850. Other kit about  £50 tops.

[TerryE]

@joe90, if you have your ASHP on its pallet, then you I assume that you selected and procured it yourself and  did a self-install (or used a local jobbing plumber to do this with you as the design authority.) -- one of the "other members here" that I mentioned.  But you also need to read the maintenance instructions and do said maintenance -- or not bother an accept that this might in turn shorten the life of the ASHP.   If I do go the ASHP route then I will follow this lead. 

 

The £5K + £200 p.a. was what I was suggesting (and I accept that I might be wrong) if I did as many home builders do and go somewhere like the Mitsubishi Ecodan Registered Installers page and got a complete quote and budgetary quote for annual maintenance. 

 

Any maintenance contract which involves an annual site visit will cost at least £100 and maybe £150 just for the engineer to turn up and leave.  Doing anything costs extra

Edited November 22, 2018 by TerryE

[Ricco]

So i am being convinced that an ASHP for the UFH and a SunAmp for the DHW might be a better solution, but it will depend on the outlay cost of buying these.

 

I have been in touch with a few renewable companies and the cost of an ASHP is frightening, in fact their quotes have done a very good job in nearly convincing me to go oil!

 

Would anyone recommend somewhere to buy an ASHP monoblock 9kw or 12wk for about the cost of an oil boiler!? @Declan52 and @joe90 mentioned prices that seem a lot more appealing!!

 

 

[newhome]

1 minute ago, Ricco said:

I have been in touch with a few renewable companies and the cost of an ASHP is frightening, in fact their quotes have done a very good job in nearly convincing me to go oil!

 

Tell me about it - it seems to be a licence to print money! Unless you want an MCS install that's eligible for RHI it's worth seeing if you can DIY it. There is this thread on the go currently ... 
 

 

 

[Declan52]

 The most important thing to consider is can you get someone to install the ashp and all is bits and  commission it and get it working as it's meant to be.  You can easily buy the unit and all its bits from ebay but as you have read on here countless times its the quality of the  installation that will count the most. 

 

[joe90]

@Ricco just did a quick search on Ebay and found this, https://www.ebay.co.uk/itm/FREE-LG-Air-Source-Heat-Pump-FREE-Solar-batteries-Installed/253975413998?hash=item3b221d44ee:g:h2kAAOSwjXBbuyE0 equates to £1600 over 7 years, I have not read the small print but it looks a good deal. I found a Kingspan 4 Kw ASHP and paid £850 for it and bought all the bits and installed it myself (with a bit of help from a neighbour plumber). If you read my threads it was not an easy journey and I had a few setbacks but I believe (now it’s working) that it was worth the punt.

[vfrdave]

@joe90 living in NI Im not sure that @Ricco or myself would be eligible to apply for what seems to be an RHI based offering on your ebay link

[PeterW]

35 minutes ago, Ricco said:

So i am being convinced that an ASHP for the UFH and a SunAmp for the DHW might be a better solution, but it will depend on the outlay cost of buying these.

 

I have been in touch with a few renewable companies and the cost of an ASHP is frightening, in fact their quotes have done a very good job in nearly convincing me to go oil!

 

Would anyone recommend somewhere to buy an ASHP monoblock 9kw or 12wk for about the cost of an oil boiler!? @Declan52 and @joe90 mentioned prices that seem a lot more appealing!!

 

 

 

Daikin 9kw is shy of £3k which is same as a boiler and tank. 

 

https://www.orionairsales.co.uk/daikin-ebhq008bbv3-air-to-water-heat-pump-monobloc-systems-9kw310000btu-240v50hz-7786-p.as

 

Thats from a google search too - can be had for less.

 

Ask for a non MCS install price as that will keep the price down. 

 

 

[Declan52]

All our rhi schemes are  closed here. Think it will be a long time before we get another as well. 

 

[newhome]

Just now, Declan52 said:

All our rhi schemes are  closed here. Think it will be a long time before we get another as well. 

 

 

Makes no sense as to why the installs are so expensive in NI then. I get that the installers here want to cash in on the RHI (in my case they wanted the entire 7 years of payments to install the thing as far as I could see given the quote was 14.6k) but surely the take up of these pricey installs must be very low without the RHI deal? 

 

[Declan52]

When I was doing mine when I added it all up and worked out doing the  bits without the rhi it was  costing me  about £1000 extra to  go  down that route.  They had  itemised the  bill and most of it was  paperwork things.  I guess it was just  a method of covering what ever costs they had to join and stay mcs  registered. I didn't mind as  my payments over the  7 years covered that  extra payment easily. 

Once the  rhi stopped here  the  whole renewable energy sector just  died.  Very very few companies left so it's things like  servicing your system by an accredited guy that becomes difficult.  You have to use these to stay on the scheme. 

[joe90]

51 minutes ago, vfrdave said:

@joe90 living in NI Im not sure that @Ricco or myself would be eligible to apply for what seems to be an RHI based offering on your ebay link

 

AH just read the small print, didn’t realise THEY got the RHI payment ?. Like most I did not bother with RHI as my house is built too well!!!. 

Edited November 24, 2018 by joe90

[Stones]

@Ricco

 

Have a look at the company linked to in this thread:

 

Notionally trade only but were happy to supply to me as a self builder.

[vfrdave]

Having looked at this some more the cost of ashp (size dependent), install kit and controller is largely comparable to oil boiler, tank, pipework etc give or take a few hundred. 

How DHW is dealt with is potentially where the cost comes. A cylinder would largely be equivalent cost wise to a thermal store for oil boiler. Sunamp charged by economy 7 is an attractive proposition but largely more expensive.

To say my head is in a spin is an understatement. My head is melted.