ASHP with large thermal store (for load shifting)

[TW9]

13 hours ago, SteamyTea said:

And they store energy at a useful temperature.

Yes. They phase change at 45 degrees which is fine for a heating system.

[ReedRichards]

52 minutes ago, TW9 said:

Yes. They phase change at 45 degrees which is fine for a heating system.

So how do you specify one of those (instead of the standard product which has a transition temperature of about 56 C)?

[SteamyTea]

58 minutes ago, ReedRichards said:

So how do you specify one of those (instead of the standard product which has a transition temperature of about 56 C)?

Work out your most likely thermal loads (you need to do this anyway) and then see what the capacity, in kWh, they can supply.

[ReedRichards]

2 hours ago, SteamyTea said:

Work out your most likely thermal loads (you need to do this anyway) and then see what the capacity, in kWh, they can supply.

Sorry, i should have written "order" rather than "specify".  What i mean is, how do you ensure you get the right Phase Change Material when Sunamp seem reluctant to acknowledge there are different options?

  

[SteamyTea]

Just now, ReedRichards said:

Sorry, i should have written "order" rather than "specify".  What i mean is, how do you ensure you get the right Phase Change Material when Sunamp seem reluctant to acknowledge there are different options?

  

No idea.  Ask their technical department or the technical sales at one of their agents.

From my understanding, Sunamp lost the plot a few years back when they got involved with a large marketing company.

@Andrew Bissell - Sunamp may still look on here, or not.

[SteamyTea]

@ReedRichards

Just had a thought while I was up in the loft tidying.

 

Too high a temperature is not really a problem as your system design can just use a temperature blending valve.

 

So really the things to look at if seriously considering a Sunamp are the kWh price and the size they take up.  You can always parallel them up for extra storage.

[ReedRichards]

@SteamyTea

A heat battery is cheaper than an electrical battery, kWh for kWh, so if the Sunamp product, or something similar, was cheap enough I would be tempted to get one.  But I don't have a night rate tariff or a meter capable of running one so I could only use a Sunamp in conjunction with my solar PVs and it would only benefit me on a cloudy day or two following a day of sunshine (like today, as it happens).  If there were 50 such days a year and i could save myself £1 each day then for me the payback period would still be too long. 

[SteamyTea]

25 minutes ago, ReedRichards said:

But I don't have a night rate tariff or a meter capable of running one

You can get one.

[JohnMo]

Water cylinder is why cheaper than a sunamp. £3k v £1k size for size, spend a little more get an A rated cylinder like OSO, the heat loss is low also.

 

300l, start temp 30 finish temp 56, circa 9 kW.  Which takes back to big buffers/ thermal stores.

[ReedRichards]

9 hours ago, SteamyTea said:

You can get one.

I checked a few years ago and nobody nearby had a smart meter that actually worked.  If I try to apply for one online from my electricity supplier (Eon.next) the link dumps me back at the overview page so I really don't think I can.

 

 

[SteamyTea]

7 hours ago, ReedRichards said:

I checked a few years ago and nobody nearby had a smart meter that actually worked. 

I have E7 on a non smart meter.

EDF keep pressing me to get it changed, and I think next year the radio system that switches the supply is being turned off, so maybe they are not installing the old radio switches.

I would call them up and ask.

[Nickfromwales]

On 29/05/2022 at 23:29, ReedRichards said:

Possibly they do but you have to search their literature quite hard to even find out what the transition temperature of their standard PCM is.  You would think that his page https://sunamp.com/savings-add-up-with-economy-10-ashp-sunamp/ would mention the need for a different PCM with a lower transition temperature, but it doesn't.

Are they producing a lower temp PCM unit currently? They state these are compatible with a HP, but tbh that just means the owner needs to get the flow temp up past 58oC ( phase change is at 58 hence the name "PCM58" ) but you need to go higher to get a discernible recharge rate. When heating these from a wet external source ( whatever guise that took ) I usually set it to be at or close to 75-80oC so the unit would recharge ( change state ) as quickly as possible. HP's must have to run for a LOT longer to get the same transition, so at lower CoP for a lot longer I assume?  

[Nickfromwales]

On 30/05/2022 at 11:53, ReedRichards said:

Sorry, i should have written "order" rather than "specify".  What i mean is, how do you ensure you get the right Phase Change Material when Sunamp seem reluctant to acknowledge there are different options?

  

They're reluctant to discuss anything with anyone on spec's, but some members of the public have PCM 34's ( 34 IIRC ) and a very select few have PCM 43's. Gagging orders were signed to get the 43's, as they were basically out for R&D only, so there's little to no feedback anywhere on those I expect.

 

On 30/05/2022 at 07:47, TW9 said:

Yes. They phase change at 45 degrees which is fine for a heating system.

Where is that stated? A link would be useful, thanks.

 

 

I was having a beer with one of their current 'approved installers' recently, and he was saying how much he struggles to get any info / feedback / response from SA regarding the correct specification of a particular unit for a particular circumstance. With the Thermino now being the current working revision of the Suamp Uniq, with many options / models for X,Y & Z, you think this would be under control by now, but it doesn't sound as if they're staffed to deal with anything other than orders and shipping. And that's from someone who started that conversation without provocation from me. I pretty much pre-empted every word that he said, as he was saying it, so little has changed afaic.

 

They've never wanted to deal with questions for individuals, just mass sales for dumb clients who don't know or understand why they've chosen this product, other than a silver-tongued salesman told them many, many wonderous things about them, but not one of them a historian I expect..... A colleague of mine is on his 3rd unit atm, with his new replacement having been delivered after a battle over warranty.

[HughF]

10 hours ago, Nickfromwales said:

They're reluctant to discuss anything with anyone on spec's, but some members of the public have PCM 34's ( 34 IIRC ) and a very select few have PCM 43's. Gagging orders were signed to get the 43's, as they were basically out for R&D only, so there's little to no feedback anywhere on those I expect.

 

Where is that stated? A link would be useful, thanks.

 

 

I was having a beer with one of their current 'approved installers' recently, and he was saying how much he struggles to get any info / feedback / response from SA regarding the correct specification of a particular unit for a particular circumstance. With the Thermino now being the current working revision of the Suamp Uniq, with many options / models for X,Y & Z, you think this would be under control by now, but it doesn't sound as if they're staffed to deal with anything other than orders and shipping. And that's from someone who started that conversation without provocation from me. I pretty much pre-empted every word that he said, as he was saying it, so little has changed afaic.

 

They've never wanted to deal with questions for individuals, just mass sales for dumb clients who don't know or understand why they've chosen this product, other than a silver-tongued salesman told them many, many wonderous things about them, but not one of them a historian I expect..... A colleague of mine is on his 3rd unit atm, with his new replacement having been delivered after a battle over warranty.

Cool energy have been playing around with a regular pcm58 unit and from chatting to them they said that they did manage to get some charge into them at 55deg flow. They did offer it to me for cheap for experimenting but it wasn’t quite cheap enough.

 

They will shortly have their units working with a pcm43 unit, apparently.

 

There we’re a couple of sunamps on Facebook a few months back, £300 each, but I didn’t get to Birmingham in time and they’ve now gone.

[SteamyTea]

4 hours ago, HughF said:

they said that they did manage to get some charge into them at 55deg flow

Thy should accept some charge at below the phase change temperature, but the heat capacity will be lower.

 

[ReedRichards]

14 hours ago, Nickfromwales said:

...A colleague of mine is on his 3rd unit atm, with his new replacement having been delivered after a battle over warranty.

I would have hoped there was not much to go wrong; what happened?

[h_copter]

Hi @apesort what did you end up doing with your ASHP and Thermal Store? I also have a large TS (2000litre) that is currently charged from a wood gassification boiler. I am planning on replacing it with ASHP and trying to decide whether to keep the TS or ditch it. The main motivation for keeping the TS is that I can charge it using offpeak electricity (6hrs@7p vs 28p daytime) and I can also suppliment the ASHP with immersions (6kW currently but can increase to 18kW), all at 7p. This means any heat efficiency losses are more than offset by the cost efficiency gain of almost 400%. DHW is in the same circuit as the rads, but also has its own solar thermal and back-up immersion. Flow temp needs to be a min of 45dC for our old house and demand during the coldest part of winter is 110kWh per 24hr. I'd be interested to know if anyone has installed a similar system. 

[JohnMo]

I would skip the thermal store, if you need 45 degs, heating the TS to 60 degs would hold 35kWh, so a small dent in your 110kWh. Also be a rubbish CoP doing 60 Deg and the ASHP may be defrost hell when you most it.

 

An unvented cylinder for DHW, and an open system for heating running WC. Put a 3 port diverter between heating and cylinder so they run different temperatures.

 

 

[Alexphd1]

@h_copter we have mixed a 22kw log gasififiaction boiler and a 9kw monobloc ashp. It has 2x 500l stainless TS that ashp heats one and log boiler heats both, also has 8m2 of solar thermal and some PV mixed in. We are currently adding fox PV batteries to the system so we can run the ashp for a few hours during the day. I don't know if its the most efficient system but it certainly works. We are trying to utilise off-peak electricity.

[Michael_S]

IS it not possible to get 15kwh of battery for £1500 and £500 for an invertor? - that electricity can then give you 45kwh during the day from your heat pump?