Horizontal cylinder or Sunamp?

[Alexx]

I've been quietly reading lots of topics here about Sunamp as I was considering it an alternative for energy storage in my loft eaves. I should be able to get a horizontal cylinder to fit, just checking this at the moment with a mock up cardboard.

 

The idea of Sunamp is great, but it seems the execution is poor. From what I can see it seems a bit of a beta/alpha product released to the masses with a "network" of installers and with little end user support when things go wrong. I can't find much on youtube about people showing their own installations, which leads me to believe no one does it.

 

So back to my original plan, I can get a 300L tank in the loft, but everyone says for a heat pump, that is a no go. From what I can see, I just need a cylinder with a large coil made specific for a low temperature system, and perhaps a de-stratification pump. yeah, 300L horizontal won't be the same as a 300L vertical, but I have no other option.

Any thoughts? Should I avoid Sunamp like a plague?

[DamonHD]

A Sunamp Thermino is working well for me:

 

https://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html

 

Rgds

 

Damon

[dpmiller]

can your loft take the weight of either?

[ProDave]

Horizontal cylinder should be okay, at least you are lifting it up into the loft empty.

 

A sun amp weighs a LOT.  Best of luck lifting that into aloft and making the loft string enough.  I have heard of people struggling to get one up an ordinary staircase, let alone somehow up into a loft.

[JohnMo]

Not even certain a sunamp even works with a heat pump, they say they do, but the heat pump specific one requires a minimum flow temp of 65? Not really sure they would be much use.

[Iceverge]

Beat me to it @JohnMo. 

 

You'll get poor COP for an ASHP with a Sunamp as you'll be running it too hot. 

 

They really work best with higher temp inputs like direct electric, gas etc. 

 

How much space does your loft allow you? Could you parallel smaller tanks? 

 

ASHP works best with a

Big cylinder 

Big Coil

Low storage temps. 

 

 

[SteamyTea]

9 hours ago, Alexx said:

I just need a cylinder with a large coil made specific for a low temperature system, and perhaps a de-stratification pump. yeah, 300L horizontal won't be the same as a 300L vertical, but I have no other option.

What makes you think there is a performance difference because of orientation? 

[Alexx]

13 hours ago, DamonHD said:

A Sunamp Thermino is working well for me:

 

https://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html

 

Rgds

 

Damon

Thanks, interesting report about it. I heard that is can only do full blast or nothing, like 2.8kw. Is that true? Does it not modulate?

 

14 hours ago, dpmiller said:

can your loft take the weight of either?

 

Yes I've put 8x2s every 200mm centres, they are about 1.8m long, then 22mm chipboard. One side on a steel beam the other side on the blockwork

 

13 hours ago, ProDave said:

Horizontal cylinder should be okay, at least you are lifting it up into the loft empty.

 

A sun amp weighs a LOT.  Best of luck lifting that into aloft and making the loft string enough.  I have heard of people struggling to get one up an ordinary staircase, let alone somehow up into a loft.

 

That is a very good point, I guess I can strap it and get 4 people to help but still a tiny dense box to manage with no handles.

 

11 hours ago, JohnMo said:

Not even certain a sunamp even works with a heat pump, they say they do, but the heat pump specific one requires a minimum flow temp of 65? Not really sure they would be much use.

 

That is the part the makes me feel it is a no go. they have 3 models for samsung, daikin and vaillant, but they all need to ruin max temp from what I can see. The samsung needs to be modded to achieve sugh high temperature and I think that would negatively impact the COP.

 

11 hours ago, Iceverge said:

Beat me to it @JohnMo. 

 

You'll get poor COP for an ASHP with a Sunamp as you'll be running it too hot. 

 

They really work best with higher temp inputs like direct electric, gas etc. 

 

How much space does your loft allow you? Could you parallel smaller tanks? 

 

ASHP works best with a

Big cylinder 

Big Coil

Low storage temps. 

 

 

 

Slope starting from 95cm from floorboard, then going down at around 30 degrees, I'll take some pictures and post here once I do the cardboard mock p. It will just fit a horizontal, it would not fit any type of vertical. My idea is to store at 55c max or just go to that temp from time to time to kill legionella, 300+ litres, de-strat pump, the largest coil possible, the small feet possible to keep the cylinder in place without increasing the height. 

 

5 hours ago, SteamyTea said:

What makes you think there is a performance difference because of orientation? 

 

the stratification of water, as it is a larger surface compare to a vertical cylinder, that it will be less useable volume of water in practice. Energy loss wise, should be exactly the same, it is same cylinder just turned around.

[Alexx]

I decided to call Sunamp this morning and speak to someone on sales to get some better understanding about their product. Funny enough, no one to take the call... Really?!?! 

[DamonHD]

1 hour ago, Alexx said:

Thanks, interesting report about it. I heard that is can only do full blast or nothing, like 2.8kw. Is that true? Does it not modulate?

 

The Sunamp exposes a bare resistive immersion heater, nominal 2.8kW I think yes, more like 3kW+ at my typical supply voltage.

 

Upstream I have a myenergi eddi that does modulation down to a few watts, generally from PV diversion.

 

I also top-up from grid and do not allow more than ~2kW to be drawn fron grid.

 

So the Sunamp can get the full 3kW on a very sunny day, or when my Enphase battery is able to kick in enough during a top up with 2kW from the grid.

 

Rgds

 

Damon

Edited October 16, 2023 by DamonHD

[ToughButterCup]

31 minutes ago, DamonHD said:

...

Upstream I have a myenergi eddi that does modulation down to a few watts, generally from PV diversion.

 

I also top-up from grid and do not allow more than ~2kW to be drawn fron grid.

...

 

Whats modulation please? 

 

I have an EDDI too - how, using the EDDI ,  do you specify a limit to be drawn from the grid ( in your case 2Kw) ?  I merely press Boost and let it run for an hour.  I have no idea how much that draws ..... but then I do know that two successive boosts allow us to shower and bathe from cold.

[Nickfromwales]

7 hours ago, SteamyTea said:

What makes you think there is a performance difference because of orientation? 

Manufacturers state so, I guess because heat rises and the shape doesn't lend itself to having a lot of volume over the highest part of the coil. A few installation drawings show a stratification pump (a bronze pump which goes between the hot outlet and the cold inlet, triggered when the ASHP is running in DHW mode) which stirs the cylinder up and should give very good results.

[Nickfromwales]

1 hour ago, Alexx said:

I decided to call Sunamp this morning and speak to someone on sales to get some better understanding about their product. Funny enough, no one to take the call... Really?!?! 

You have more chance of meeting the pope. As an ex installer, I noted that they were very difficult to get technical information out of, and were diabolically bad at responding to clients (unless there was an online (ergo it had an element of 'public awareness') matter which got seen to in the wink of an eye.........)  

They now actively avoid engaging with the public, and do not attend public shows / events AFAIK (other than trade events for bulk sales).

[ToughButterCup]

Here is the list of approved stockists who, according to the SunAmp website

 

Quote

Sunamp has approved product stockists and installers around the UK who can help you, as a homeowner, with thermal battery prices, installation and technical information.....

https://sunamp.com/en-gb/resellers-stockists/  downloaded  16/10/2023

 

The key term is Approved Stockists.

My Sunamp was installed by an Approved Stockist. Every bit of technical information I needed was given to me by the stockist.

 

[SteamyTea]

4 hours ago, Alexx said:

the stratification of water, as it is a larger surface compare to a vertical cylinder, that it will be less useable volume of water in practice. Energy loss wise, should be exactly the same, it is same cylinder just turned around.

 

2 hours ago, Nickfromwales said:

Manufacturers state so

I modelled it not long ago because someone asked the same question.

I think there was not much in it, and if I remember correctly, vertical had higher losses.

 

Posted August 10 (edited)

  On 10/08/2023 at 11:42, Post and beam said:

An issue put forward is that the horizontal nature of the tanks makes mixing of the hotter & colder water less efficient.

I have never seen it modelled, so hard to tell.

 

Take a cylinder with a 0.5m diameter ad a 1.2m height.

Assuming a U-Value of 0.2 W.m^-2.K^-1 

 

Volume will be 235 lt.

Surface Area will be 2.28 m² 

Base of cylinder temperature, once settled, 36°C, top of cylinder temperature 60°C.

Ambient Temperature 10°C.

 

If one assume a temperature gradient of 20K.m^-1 (about what mine is), then the power losses, when vertical, will be the sum of the top end, plus the area of the diameter (hoop), then the sum of the hoops, and finally the sum of the last band and the base area.

Using a course 0.1m down the cylinder, the power losses are 18W, or if the cylinder is unused for a day, 0.44 kWh.

 

Now lets turn the cylinder horizontally.  Working out the surface area is not quite so easy here as for every 0.1m loss in height, the end area and the hoop area do not scale in a linear fashion, so I sketched it up in CAD, sliced it, triangulated it, then worked out the dimensions.  Accumulative errors was between 1 and 8%, so shall use 4% as the error.

The cylinder power losses are now 20W, 0.49 kWh.day^-1.  A difference of 0.05 kWh.

 

The above is on a static model, but there will be some turbulence.

With a mean temperature of 48°C for the vertical temperature, the mean density of the water is 988.7 kg.m^-3, at the top of tank temperature, the density is 5.53 kg less, 4.48 kg more at the bottom.  A total of 10 kg.m^-3 difference

The horizontal cylinder only has a 12°C temperature difference (because I used the same temperature gradient of 20K.m^-1), so the density difference is only 5.6kg.m^-3.

Now without getting into Reynold Numbers and tangential surface areas, a simple way to model it would be to look at the difference in stored energy and the difference in mass as energy is the ability to do work, which can be reduced to moving a mass a distance.

The vertical cylinder will have 233 kg of water in it, the horizontal one 232.4 kg, so 0.6 kg less.

To move 1 kg of water, 1 metre, will take 1 joules of energy.  So to move 232.4 kg 1.2 metres will take 279.6 J in the vertical cylinder.  There is only 0.5 metres of height in the horizontal cylinder, so 116.2 J, so the turbulence losses will be in thee order of 42% less.

 

So I would not worry about the cylinder orientation.

 

I am going outside to sand some wood now the glue has set.

[ToughButterCup]

Very interesting post @SteamyTea .....

[Iceverge]

Is this green area what you mean by 95cm sloping away at 30 deg? 

 

 

Looking at the tempest website then their 300l Heat pump horizontal cylinder should fit just about. There won't be much to spare if you need to stay inside your 950mm line for fittings however. 

 

 

 

The 170l would be better size wise but you may need a pair of them 

 

 

 

I'm sure all cylinder manufacturers can alter the position of ports as necessary anyway. 

 

 

 

 

[Iceverge]

 

As a slightly left field idea.....

 

How about 2 * lower capacity direct horizontal cylinders. Run the primary water through them from the ASHP. 

 

Then use a flow switch on the DHW draw off to trigger a pump to pump the primary water through a plate heat exchanger to heat the DHW. 

 

 

 

 

 

 

[ProDave]

28 minutes ago, Iceverge said:

 

As a slightly left field idea.....

 

How about 2 * lower capacity direct horizontal cylinders. Run the primary water through them from the ASHP. 

 

Then use a flow switch on the DHW draw off to trigger a pump to pump the primary water through a plate heat exchanger to heat the DHW. 

 

 

You have just invented the "Thermal Store" with all the issues that has in relation to use with an ASHP.  Namely as you draw heat out of them you reduce the temperature of the water in the store, thus reducing the effective capacity vs a hot water tank, that delivers near constant temperature water right to the end.

[Iceverge]

Well spotted @ProDave, I don't think I've every had an original thought!

 

It would be an adaptation of a "heat bank " rather than a thermal store. For an equal volume of primary water they typically produce more DHW than a coil in tank thermal store at the difficulty of having to pump the primary water through a PHE. 

 

I have never seen one with an ASHP but I don't see why it couldn't work. 

 

 

[DamonHD]

15 hours ago, ToughButterCup said:

 

Whats modulation please? 

 

I have an EDDI too - how, using the EDDI ,  do you specify a limit to be drawn from the grid ( in your case 2Kw) ?  I merely press Boost and let it run for an hour.  I have no idea how much that draws ..... but then I do know that two successive boosts allow us to shower and bathe from cold.

Yes, I have the eddi Grid Limit set to 8A, ie ~2kW:

 

https://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html#2022-09-23

 

When doing solar PV diversion the eddi regulates/modulates the amount sent to the Sunamp so as not to cause any import from the grid.

 

When doing (boost) top-up from grid the eddi regulates/modulates the amount sent to the Sunamp so as not to exceed the specified 8A limit on importing from the grid.

 

Rgds

 

Damon

Edited October 17, 2023 by DamonHD

[Alexx]

On 16/10/2023 at 12:37, Nickfromwales said:

Manufacturers state so, I guess because heat rises and the shape doesn't lend itself to having a lot of volume over the highest part of the coil. A few installation drawings show a stratification pump (a bronze pump which goes between the hot outlet and the cold inlet, triggered when the ASHP is running in DHW mode) which stirs the cylinder up and should give very good results.

 

That seems to be the general opinion I've gathered, as long there is a de-strat pump running when the cylinder is being charged, there will be not that much difference. After I've considered all options and the lack of commitment/info from Sunamp, I've decided to stick to a horizontal cylinder. I'm just trying to decide which brand/model I should go for.

 

On 16/10/2023 at 15:28, SteamyTea said:

 

I modelled it not long ago because someone asked the same question.

I think there was not much in it, and if I remember correctly, vertical had higher losses.

 

Posted August 10 (edited)

  On 10/08/2023 at 11:42, Post and beam said:

An issue put forward is that the horizontal nature of the tanks makes mixing of the hotter & colder water less efficient.

I have never seen it modelled, so hard to tell.

 

Take a cylinder with a 0.5m diameter ad a 1.2m height.

Assuming a U-Value of 0.2 W.m^-2.K^-1 

 

Volume will be 235 lt.

Surface Area will be 2.28 m² 

Base of cylinder temperature, once settled, 36°C, top of cylinder temperature 60°C.

Ambient Temperature 10°C.

 

If one assume a temperature gradient of 20K.m^-1 (about what mine is), then the power losses, when vertical, will be the sum of the top end, plus the area of the diameter (hoop), then the sum of the hoops, and finally the sum of the last band and the base area.

Using a course 0.1m down the cylinder, the power losses are 18W, or if the cylinder is unused for a day, 0.44 kWh.

 

Now lets turn the cylinder horizontally.  Working out the surface area is not quite so easy here as for every 0.1m loss in height, the end area and the hoop area do not scale in a linear fashion, so I sketched it up in CAD, sliced it, triangulated it, then worked out the dimensions.  Accumulative errors was between 1 and 8%, so shall use 4% as the error.

The cylinder power losses are now 20W, 0.49 kWh.day^-1.  A difference of 0.05 kWh.

 

The above is on a static model, but there will be some turbulence.

With a mean temperature of 48°C for the vertical temperature, the mean density of the water is 988.7 kg.m^-3, at the top of tank temperature, the density is 5.53 kg less, 4.48 kg more at the bottom.  A total of 10 kg.m^-3 difference

The horizontal cylinder only has a 12°C temperature difference (because I used the same temperature gradient of 20K.m^-1), so the density difference is only 5.6kg.m^-3.

Now without getting into Reynold Numbers and tangential surface areas, a simple way to model it would be to look at the difference in stored energy and the difference in mass as energy is the ability to do work, which can be reduced to moving a mass a distance.

The vertical cylinder will have 233 kg of water in it, the horizontal one 232.4 kg, so 0.6 kg less.

To move 1 kg of water, 1 metre, will take 1 joules of energy.  So to move 232.4 kg 1.2 metres will take 279.6 J in the vertical cylinder.  There is only 0.5 metres of height in the horizontal cylinder, so 116.2 J, so the turbulence losses will be in thee order of 42% less.

 

So I would not worry about the cylinder orientation.

 

I am going outside to sand some wood now the glue has set.

 

I'm technical, but this definitely goes beyond my understanding  

I can grasp the idea, thanks for the extensive write up. I'll definitely re-read this many times once I understand the physics a bit better.

 

On 16/10/2023 at 21:04, Iceverge said:

Is this green area what you mean by 95cm sloping away at 30 deg? 

 

 

Looking at the tempest website then their 300l Heat pump horizontal cylinder should fit just about. There won't be much to spare if you need to stay inside your 950mm line for fittings however. 

 

 

 

The 170l would be better size wise but you may need a pair of them 

 

 

 

I'm sure all cylinder manufacturers can alter the position of ports as necessary anyway. 

 

 

 

 

 

I've been checking several models, they can customise the cylinder a bit and get the immersion heater on the side of the body, or even the dome. The rafters are 27.5 degrees.

 

This is my space, with a 600x600 cardboard cut to give a better idea:

[Alexx]

On 16/10/2023 at 21:12, Iceverge said:

 

As a slightly left field idea.....

 

How about 2 * lower capacity direct horizontal cylinders. Run the primary water through them from the ASHP. 

 

Then use a flow switch on the DHW draw off to trigger a pump to pump the primary water through a plate heat exchanger to heat the DHW. 

 

 

 

 

 

 

 

As an alternative to use 2 smaller diameter cylinders you mean?

[SteamyTea]

7 minutes ago, Alexx said:

definitely re-read this many times once I understand the physics a bit better

Good, it is too easy to mark one's own homework.

 

I think that the biggest issue is where the hot water leaves the cylinder, normally at the top, initially the hottest point, horizontal cylinder it comes from the mid point, so the median temperature, though it may be the mean temperature.

Edited October 19, 2023 by SteamyTea

[Alexx]

So I've got some additional technical details so far:

Telford:

 

Fabdec

 

 

The guys from Joule so far have been useless, not technical details, all calls I make always end up speaking to someone that has zero knowledge. I get promised the "email" that never comes with all technical details for 3 days already, after 5 phone calls.

 

I'm leaning to Telford so far as the standard horizontal heat pump cylinder is around £820 + VAT, I'm just waiting to confirm the cost to get the immersion heater on the side instead. Fabdec coil design does not seem that large to me, but I could be wrong. I just wish the coil could go further to each end of the cylinder.

 

Joule gave me a cost of £2800+ but I found it for around £1800, but still without any tech details, I can't consider it.

 

I'm now waiting for a few others like UKCylinders, World Heat cylinders, newawk and macdonald, then hopefully I can make a decision and buy it.