Sunamp heat battery

[Dreadnaught]

25 minutes ago, JSHarris said:

buffer heat capacity

 

@JSHarris, @TerryE describes how he uses the concrete slab as his buffer. Is that not a better solution for you? Just transfer the heat for space heating straight into the slab? (I am sure that you will have a good explanation why not )

[Jeremy Harris]

10 minutes ago, Dreadnaught said:

 

@JSHarris, @TerryE describes how he uses the concrete slab as his buffer. Is that not a better solution for you? Just transfer the heat for space heating straight into the slab? (I am sure that you will have a good explanation why not )

 

I do this for heating, the slab holds a fair bit of heat. 

 

Our buffer tank really only pre-heats our hot water, that's what it's really there for.  It is heated to 40 deg C by the ASHP, which keeps the heat pump working at high efficiency (no de-icing cycling) and then I have a plate heat exchanger (PHE) and flow actuated pump connected to the buffer.  Whenever a hot tap is opened, the flow switch that's in the feed to the hot water manifold turns on a pump that circulates water from the top of the buffer through the PHE and back to the bottom of the buffer tank.  Cold mains water flows through the other side of the PHE, is pre-heated to close to the buffer temperature and then flows to the Sunamp PV.  This means that the Sunamp PV only has to raise the temperature of the water from around 35 deg C or so to 58 deg C or so, and it's then mixed down to around 45 deg C with cold water before going to the taps.  The advantage is that the Sunamp PV doesn't have to supply so much heat to the incoming water, so has it's effective capacity more than doubled.  Pre-heated water is relatively cheap to heat, as the ASHP seems to run with a coefficient of performance (COP) of between 3.5 and 4, so for each kWh of pre-heated water we only use around 0.25 to 0.28 kWh of electricity, or in cost terms instead of 1 kWh costing about 15p, it only costs about 4p.

[Dreadnaught]

1 hour ago, JSHarris said:

Our buffer tank really only pre-heats our hot water

 

That makes eminent sense. Thanks Jeremy.

[Nickfromwales]

18 hours ago, le-cerveau said:

 

The PCM34 batteries will be charged by my ASHP at around 40^oC and the PCM58 batteries will be charged by the boiler at around 65^oC.

The UFH will take a feed from the PCM 34 batteries (same input as the ASHP).

DHW will be pre-heated by the PCM34 Batteries then the PCM58 batteries.

Effectively the PCM34 batteries are doing the same as @JSHarris buffer and the PCM58 batteries as is SunAmp PV.

plumbing diagram below:

 

Ok. With so much storage at the higher cell range, do you really think you need the gas boiler? Already having the ASHP would have made me kick the gas into touch for sure. 

Do you have PV?

Also valve 'T' ( 49-55oC ) is that a TMV?  Ive designed two so far with a HR pump but ive decided to pulse heat into the hot loop ( via a stat on the hot manifold in those specific cases ) rather than run for any duration.

[le-cerveau]

The boiler is already in, temporarily used as a heat source, the ASHP not yet installed.  I know it is belt and braces, and it will stay for now, but in the future I may re-evaluate it.

 

I have 9.25kW of PV.

 

Yes the 'T' for Thermostatic, is the outlet valve as the units I have don't have a TMV like the SunAmp PV's.  The intention is to run an intelligent circulating pump such as the Grundfos Comfort.

[readiescards]

Do the Sunamps have any service/maintenance cost? 

 

I was shocked to find my immersion tank requires an 'annual service' visit just to keep its 10 year warrenty - seems like an excuse for the plumber to visit, tap the tank a couple of times, have a cup of tea and charge me £150 every year :-( 

Edited March 7, 2018 by readiescards
spelling

[Jeremy Harris]

1 hour ago, readiescards said:

Do the Sunamps have any service/maintenance cost? 

 

I was shocked to find my immersion tank requires an 'annual service' visit just to keep its 10 year warrenty - seems like an excuse for the plumber to visit, tap the tank a couple of times, have a cup of tea and charge me £150 every year :-( 

 

 

If it's an unvented system then it's building regs that require/suggest the annual inspection, specifically Part G3, and is buried in the detail referred to here:

 

Quote

3.22 Any unvented hot water storage system
up to 500 litres and less than 45kW should be in
the form of a proprietary hot water storage
system unit or package. The package and
components should be appropriate to the
circumstances in which they are used and should
satisfy an appropriate standard that will ensure
the requirements of regulation G3(2) and G3(3)
will be met (e.g. BS EN 12897:2006 Water Supply.
Specification for indirectly heated unvented (closed)
hot water storage systems or BS 6700:2006 +
A1:2009 Design, installation, testing and
maintenance of services supplying water for
domestic use within buildings and their curtilages).

 

It's the "maintenance of services" bit that often specifies an annual service, for safety reasons, as it's a pressure vessel.

 

The Sunamp has too small an internal pressurised volume to fall within these regulations, so is, AFAIK, exempted from them, under this section of Part G3:

 

Quote

3.19 Water heaters with a capacity of 15 litres
or less that have appropriate safety devices for
temperature and pressure will generally satisfy
the requirement set out in G3(3).

 

 

 

[Nickfromwales]

2 hours ago, readiescards said:

Do the Sunamps have any service/maintenance cost? 

 

I was shocked to find my immersion tank requires an 'annual service' visit just to keep its 10 year warrenty - seems like an excuse for the plumber to visit, tap the tank a couple of times, have a cup of tea and charge me £150 every year :-( 

The only 'early fail' component in the dual port SA units is the electrical immersion heater which they say should be good for 10 years, and iirc is warrantied accordingly. 

They've actually adopted a better setup IMO and have chosen to fit 3 x 1kw immersions rather than a single 3kw one so triple redundancy. Probably to do with a more even heat transfer characteristic. 

[Nickfromwales]

 

 

One observation here would be the non return valve on the ASHP flow. I think that would need to be a 2-port motorised valve as I think theres a strong chance of the CH flow pump sucking water through the NRV and cycling heated water through the ASHP when its not in use. Or use a 3-port W-plan diverter valve to tee the two pipes together. then its one or the other with the same result as 2 x 2-port. 

[le-cerveau]

That is not the final setup, this is it: (heating only shown)

The ASHP defaults to the Low Loss Header (unless supplying heat), motorised valve controlled by the ASHP. (cooling mode but no call)

When drawing heat to the house the other motorised valve connects to the PCM34 cells (via a mixing valve) to draw heat, if the Cells are also calling for heat then the ASHP will also be supplying heat (Valve change over) so heat will come from the ASHP and some into recharging the Cells.

When no call for heat (from house) the the motorised valve (controlled by thermostat) sets the flow to the LLH and water simply circulated round the system, may possibly bypass through the ASHP, but but not an issue as when the PCM34 cells call for heat but the house doesn't the ASHP valve isolated the LLH from the ASHP.

If the house needs cooling then the ASHP provides cool water to the LLH and it flows on through the UFH pipes.

 

That is the theory anyway!!! (hopefully)

[Dudda]

1 hour ago, le-cerveau said:

That is not the final setup, this is it: (heating only shown)

The ASHP defaults to the Low Loss Header (unless supplying heat), motorised valve controlled by the ASHP. (cooling mode but no call)

When drawing heat to the house the other motorised valve connects to the PCM34 cells (via a mixing valve) to draw heat, if the Cells are also calling for heat then the ASHP will also be supplying heat (Valve change over) so heat will come from the ASHP and some into recharging the Cells.

When no call for heat (from house) the the motorised valve (controlled by thermostat) sets the flow to the LLH and water simply circulated round the system, may possibly bypass through the ASHP, but but not an issue as when the PCM34 cells call for heat but the house doesn't the ASHP valve isolated the LLH from the ASHP.

If the house needs cooling then the ASHP provides cool water to the LLH and it flows on through the UFH pipes.

 

That is the theory anyway!!! (hopefully)

Are you a plumber or mechanical engineer that wants this system or is it just me that thinks this seam overly complicated?

ASHP, boiler, PV, Sunamps (x2 types), all the motorized valves, pumps and controls. With all this kit will you ever get payback?

[Nickfromwales]

ASHP : for cooling.

Boiler : Existing ( but 100% completely unnecessary ). 

Low loss header : Probably way OTT. 

Sunamps : No brainer, and size / qty perfect IMO. 

Pv : The more the merrier. 

 

Id like to see a final design before this goes to print as you may well be leaking heat which would start to make things uneconomical to run when the PV isn't effective. The 2-port on the ASHP feed is a no-brainer.  

When the ASHP gets fitted Id completely redesign the installation to suit a no-gas solution ( with the gas boiler going on gumtree ). 

Utterly pointless having the gas boiler when the ASHP can be ramped up for emergency / boost to the PCM58's.

Have a rethink @le-cerveau   

 

[le-cerveau]

5 minutes ago, Nickfromwales said:

The 2-port on the ASHP feed is a no-brainer.

Not quite sure where you mean with this?

6 minutes ago, Nickfromwales said:

Low loss header : Probably way OTT.

Specified by ASHP manufacturer to approve instillation, so I incorporated it into the overall running design.

[Nickfromwales]

4 hours ago, le-cerveau said:

Not quite sure where you mean with this?

Specified by ASHP manufacturer to approve instillation, so I incorporated it into the overall running design.

My mistake, was referring to the first schematic. 

 

Did they specify the LLH because of the gas boiler ? I fear your spending good money after bad by designing the system with the gas boiler included. 

Id ditch the gas boiler when fitting the sunamps and heat them with electricity only until your ASHP is commissioned. 

The ASHP can provide high grade heat for the PCM58's so I really think it's a bad / uneconomical decision to keep the gas boiler, even if it's there already.

TBH, feeding the PCM58 units with grid electricity, rather than the ASHP, ( eg in times of no PV generation ), wouldn't be ridiculous, but a lot of the year the energy for the Sunamps will be PV based, so using the ASHP to bridge any gap that removing the boiler creates won't break the bank ( but will save £££'s on the capital installation costs and reduce complexity for controls ).

 

[Jeremy Harris]

Personally, I don't like the idea of a LLH working at a low differential temperature.  I chose to use an adjustable pressure bypass to overcome the possible problem of the ASHP flow being momentarily shut off, and am convinced it's a lower loss solution.  LLHs work very well with a relatively high differential temperature between flow and return, but they do cause mixing as the differential temperature decreases; it's inevitable given that they rely on temperature driven stratification within the small chamber in order to work.

 

I've found that a carefully adjusted pressure bypass works very well with our ASHP.  It took a bit of fiddling to get the pressure adjustment right, but since then it's been faultless.

[Nickfromwales]

5 hours ago, JSHarris said:

Personally, I don't like the idea of a LLH working at a low differential temperature.  I chose to use an adjustable pressure bypass to overcome the possible problem of the ASHP flow being momentarily shut off, and am convinced it's a lower loss solution.  LLHs work very well with a relatively high differential temperature between flow and return, but they do cause mixing as the differential temperature decreases; it's inevitable given that they rely on temperature driven stratification within the small chamber in order to work.

 

I've found that a carefully adjusted pressure bypass works very well with our ASHP.  It took a bit of fiddling to get the pressure adjustment right, but since then it's been faultless.

I agree. 

I think the ASHP manufacturers just specified them because it's a quick fix for hydraulically separating two pumped circuits, where each running at different potentials. None of the bypass adjustment / commissioning that you mention then so it's a 'guaranteed simple fix' from a manufacturers POV, regardless of its cost and inefficiency considerations. 

 

[Triassic]

Just thinking ahead, what is the lead time - design to delivery of a Sunamp unit?

[Nickfromwales]

 

5 minutes ago, Triassic said:

Just thinking ahead, what is the lead time - design to delivery of a Sunamp unit?

One for @AndyT . 

 

[mike2016]

Just thinking about ways to recharge the 3rd Gen:

 

It's typically off peak electricity and solar PV isn't it? I was just wondering if it would make more sense to put the PV and off peak through an ASHP and use that to recharge the SunAmp? You could set the threshold for when PV is used which will be more variable (so you're not using more expensive daytime grid electricity to cover the difference). I like the idea of getting a better COP during the daytime with free PV and then the cooler night & off peak 'leccy. It's just that ASHP COP multiplier vs raw 1:1 charging that's very tempting. Of course there's the cost of the ASHP but still, if they got cheap enough? 

 

I was also wondering if there's any use case for solar thermal to charge the SunAmp directly - you'd loose some PV panels and the temperature would also be affected by the seasons....??

 

I see the 3rd Gen can recharge via AC or DC - any advantage to one over the other bar inverter losses? Unless you've a DC circuit in the house for lights etc would DC limit consumption to the SunAmp only - I'd imagine the AC route would open the use of power to the wider house/car etc. Would it make sense to dedicate some panels to SunAmp? 

 

I'n on mains gas so have options to consider for recharging, I'm just trying to avoid directly fossilizing (?!) my heating...! 

 

Thoughts anyone? 

[SteamyTea]

How much energy are you looking to store.

I can understand trying to reduce fossil fuel usage, but you have to be realistic about the variance of PV over an hour, day, week, and then balance that with the capital cost of storage.

[mike2016]

Say 19kWh of storage....

[DenkiJidousha]

My guess is direct solar as DC into the 3rd generation SunAmp would work nicely with a few dedicated PV panels (e.g. a minimal simple system without an inverter for a relatively small capital outlay).

 

We're almost at the end of 2018 Q1, so I'm hopeful for more official news before too long.

Edited March 14, 2018 by DenkiJidousha
fix typo

[Nickfromwales]

A bump in the Sunamp road.....

 

Communication received from AndyT as of the last 24hrs. 

Quote from an email.....

 

"A hold has been put on the PCM34 due to a corrosion issue with the type of metal used and the hot salt and I should add that this has not been the case with the PCM58.

I am sure that you understand that we must allow the chemists to investigate why this has happened and come up with a solution.

When I know more, I will naturally let you know however in the mean time you might want to consider a plan B."

 

@le-cerveau, are you aware of this yet?

 

The above information is all thats known for now, so please, no deluge of questions here as @AndyT has promised to update on the situation as and when he is in a position to do so. 

Thanks in advance. 

[le-cerveau]

34 minutes ago, Nickfromwales said:

@le-cerveau, are you aware of this yet?

Not heard anything yet!

[Nickfromwales]

50 minutes ago, le-cerveau said:

Not heard anything yet!

You just did then  

In fairness to Andy, he's kept me aware as the news has hit him, and I assume he's now got the unenviable task of systematically sifting through a lot of customer enquiries, in the order in which they were made, to convey this information. 

Im sure it's a crease that will be ironed out accordingly, but I expect there will be a significant delay in rectifying the issue and turning it around for production.