Mixergy anyone ?

[Robert Clark]

Hi Guys

 

Saw Mixergy on Fully Charged a little while ago.

 

Looks like an innovative piece of kit at first glances

 

Our hot water requirements vary from low, under normal use, to high when family visits. 

 

 

https://mixergy.co.uk/

 

Would appreciate any comments or feedback 

 

Thanks 

 

 

 

[ProDave]

Best of luck trying to predict how much hot water you are going to use and only heat just that amount.  That is the essence of what this does.  We have a 300L tank (only heated to 48 degrees) and some days that is only just enough,m other days it is ample.

 

Only heating the tank to 48 degrees normally, still allows plenty of  capacity for surplus solar PV

[Ferdinand]

Good luck.

 

I prefer Mixology (which needs some more cocktails).

Edited April 13, 2020 by Ferdinand

[scottishjohn]

as far as i  can see its very complicated for only half your water heating requirements 

you want it all in one place  .the logic of this solvis system looks bettter,change top heat unit from gas or oil for electric  and use solar thermal for all your free energy + change lower heat source for ashp  ?

they maybe even do an updated system as this has been on market for over 15years  that i know of.

the internal tubes will give far better heat stratification  in my opinion

 

Edited April 23, 2019 by scottishjohn

[scottishjohn]

quick check and yes they do a unit that can take all TYPES OF HEAT INPUT INCLUDING PV

https://www.google.com/search?q=solvismax+price&biw=1536&bih=754&tbm=isch&source=iu&ictx=1&fir=DcN8vJE9Hn3_PM%3A%2CiB1MWAiX8QQ81M%2C_&vet=1&usg=AI4_-kSEghvAnWVVKEJnQ7fbL0pDgLiYOw&sa=X&ved=2ahUKEwjSsfDr3eXhAhVkURUIHb2ABQgQ9QEwBHoECAkQBA#imgrc=K8ckQKoj-eldTM:&vet=1

[joth]

We're going with a mixergy tank, in part because plan A was sunamp but it's just looking to finicky (and, not convenient to use with a heat pump)

The current discussion on failure mode analysis and designing for line-replacement of parts has me wondering about the overcomplications of  Mixergy, I don't think it's too bad because

- we're not planning to use it to predict usage day by day, just to allow us to have effectively 200L of hot water tank but expands to 300L when there's free energy coming off the PV

- the fanciest bits of the internet connection are for the predicting the future parts. Without that I think we'll get fair use from it primarily through local schedule control. 

- if the fancy controller or cloud service eventually breaks, it just becomes a normal tank, not a dead lump of salt.

 

The only thing that does concern me is the heat plate exchanger and circulation pump assembly they use for getting most effeciency from a low temp heat pump. I have not idea how tightly the speed control for that is coupled into the rest of the controller circuit. Obviously it already had double immersion as the primary backup, but maybe it would be prudent to order with an internal coil too so we have that as a backup (I have half a mind we could warm the ufh from that, if it became necessary to use it as an E7 time-shift store).

[Robert Clark]

6 hours ago, joth said:

We're going with a mixergy tank, in part because plan A was sunamp but it's just looking to finicky (and, not convenient to use with a heat pump)

The current discussion on failure mode analysis and designing for line-replacement of parts has me wondering about the overcomplications of  Mixergy, I don't think it's too bad because

- we're not planning to use it to predict usage day by day, just to allow us to have effectively 200L of hot water tank but expands to 300L when there's free energy coming off the PV

- the fanciest bits of the internet connection are for the predicting the future parts. Without that I think we'll get fair use from it primarily through local schedule control. 

- if the fancy controller or cloud service eventually breaks, it just becomes a normal tank, not a dead lump of salt.

 

The only thing that does concern me is the heat plate exchanger and circulation pump assembly they use for getting most effeciency from a low temp heat pump. I have not idea how tightly the speed control for that is coupled into the rest of the controller circuit. Obviously it already had double immersion as the primary backup, but maybe it would be prudent to order with an internal coil too so we have that as a backup (I have half a mind we could warm the ufh from that, if it became necessary to use it as an E7 time-shift store).

 

Will you be using one of their specified installers?

[joth]

3 hours ago, Robert Clark said:

Will you be using one of their specified installers?

Still getting quotes - should know in a couple weeks

 

[Nickfromwales]

I admire the guys enthusiasm, but is this not just a re-make of the old 'bath / basin' setup of cylinders in the 70's where if you wanted hand / dish wash through the day you fed into the top loaded immersion, and if you wanted a bath you flicked the switch for the lower mounted immersion and then heated the old tank.

I'd be very interested in how much this "new technology" costs vs a standard UVC with an upper and lower immersion + additional stat  pocket.... 

[joth]

@Nickfromwales true enough, the improvement is a diffuser that helps retain the stratification even after drawing some water off, and some sensors to measure what the hot water "fill" level is. I too will be keen to get the price, vs comparably insulated and speced Newark UVC.

[Nickfromwales]

10 minutes ago, joth said:

@Nickfromwales true enough, the improvement is a diffuser that helps retain the stratification even after drawing some water off, and some sensors to measure what the hot water "fill" level is. I too will be keen to get the price, vs comparably insulated and speced Newark UVC.

Trevor at Cylinders2go will give you a good price too, if you want a comparison. He did a group purchase discount a while back for the forum posse

[Dan F]

Has anyone installed and is using a Mixergy tank? @Robert Clark what did you do in the end?

 

We are very keen to avoid a standard UVC as we won't have a gas supply and beleive that load-shifting DHW electricity demand makes a ton of sense in both winter (from cheap nightime tarriff) but also in the summer (from free PV during the middle of the day).  My understanding is that with a standad UVC this is a major challenge without reheating water in the tank as you use it, unless you want lukewarm showers.

 

Using Sunamp heat batteries is a great way to achieve i) load-shifting ii) partial charging iii) low heat-loss and all nice and compart but we've been advised that in order to get a very good flow rate and >300L capacity we'd be looking at 2 x UniQ9, and that's where Sunamp becomes less interesting because we'd be looking at almost £5000!

 

It's clear that Mixergy is not as compact as a Sunamp (not a major issue for us), and will never be able to compete on heat-loss, but it does support load-shiting and partial charging and costs less that a 1/3 of the price of 2 x UniQ9.  So, I'm really wondering if it makes any sense an extra £3,000 on Sunamps.  (I know some people will mention the G3 annual service but in reality very few people pay yearly for this service unless pherhaphs they are landlords).

 

Mixergy shared some real-world data from current installs that shows how a tank with 25% "charge", still has 58C temperature at the top, while bottom is at 12C, so it's definitly more than just marketing and an app.  Also, looks like it potentially has better control system than Sunamp with option to use their app or integrated directly via modbus.

 

Thoughts?

 

 

Edited April 13, 2020 by Dan Feist

[ProDave]

My compromise is a 300L UVC heated by the ASHP.  I have the ASHP timed to start heating DHW at 11AM to ensure reasonable solar PV veneration by then so a good chance solar PV will power it.

 

The ASHP only heats the tank to 48 degrees, still allowing plenty of headroom for surplus solar PV to heat it hotter on a good sunny day.

 

Most of us usually shower in the evening so not much HW demand in the mornings.

 

To cover the eventuality of a cool HW tank for any reason I have a 10kW modulating steible eltron instant water heater in line with the UVC output.  that too is set to 48 degrees so nromally does nothing. But if the tank is cool, either for an unexpected early shower, or simply too many people have used up all the hot water faster than the ASHP can recharge the tank, you still have hot water.

[Robert Clark]

We’re still considering Mixergy

Wouldn’t use Sunamp until they sort out customer service and communication 

 

Was about to order a Mixergy tank when CV happened and am still in communication with their local installer.

 

[Dan F]

@Robert Clark Let us know how it goes..

 

@ProDave That makes sense, just keen to do a bit more than that, but can't justify spending £5,000 on Sunamp!  Also my understanding is that a non-mixergy UVC without the careful stratification will need  a larger ASHP (to stop water going lukewarm during heavy use) meaning we'd need to be looking at 12/14kW options (when we only need max 6kW for heating).  How did you size your ASHP?

 

[ProDave]

No with no heat input, the water stays in layers so as you draw water off, it stays pretty much the same delivery temperature until it runs out.

 

It is only when you start putting heat back into the cylinder that convection starts and the contents get mixed about.

 

We have a 5kW ASHP. An 8 or 9kW would do you well.

 

Mine was sized using @Jeremy Harris heat loss calculator that showd a maximum heat input demand of just over 2kW.  5kW is about as small as you can buy.

[Dan F]

7 minutes ago, ProDave said:

No with no heat input, the water stays in layers so as you draw water off, it stays pretty much the same delivery temperature until it runs out.

 

It is only when you start putting heat back into the cylinder that convection starts and the contents get mixed about.

 

Really?  My understanding was that with a a standard UVC the incoming cold water gets mixed and so the water temperature at the top of the tank will be lukewarm by the time you've used a certain % of the tank.  This can be improved with a good inlet difuser, which some tanks have, but not all.  Do you have any way of knowing what the delivery temperature is over time without supplying heat to your tank?  Which brand?

 

Mixergy uses Newark tanks, what I'm not sure is if they use the standard Newark inlet diffuser, or if they use a custom diffuser or are doing anything else on top of this.

 

Regarding ASHP sizing: we have PHPP heating load of 3kW, but have been advised to use 6kW based on other calcs.  Issue is that if we go for a 400L tank, recoevery time of 6kW ASHP is going to be high.. which is another reason to be able to load-shift to avoid oversizing ASHP..

 

 

[ProDave]

29 minutes ago, Dan Feist said:

 

Really?  My understanding was that with a a standard UVC the incoming cold water gets mixed and so the water temperature at the top of the tank will be lukewarm by the time you've used a certain % of the tank.  This can be improved with a good inlet difuser, which some tanks have, but not all.  Do you have any way of knowing what the delivery temperature is over time without supplying heat to your tank?  Which brand?

 

Mixergy uses Newark tanks, what I'm not sure is if they use the standard Newark inlet diffuser, or if they use a custom diffuser or are doing anything else on top of this.

 

Regarding ASHP sizing: we have PHPP heating load of 3kW, but have been advised to use 6kW based on other calcs.  Issue is that if we go for a 400L tank, recoevery time of 6kW ASHP is going to be high.. which is another reason to be able to load-shift to avoid oversizing ASHP..

 

 

Not my findings.

 

The water only starts mixing when you apply some heat input that starts convection.  Perhaps my Telford tank has an inlet difuser but they don't mention it.

[Dan F]

2 hours ago, ProDave said:

Not my findings.

 

The water only starts mixing when you apply some heat input that starts convection.  Perhaps my Telford tank has an inlet difuser but they don't mention it.

 

Mmm, Pherhaps I'll have to quiz mixergy a bit more on exactly how different their tank is/isn't from a discharge/mixing perspective is., Unless @Robert Clark or @joth know?

 

[ProDave]

10 minutes ago, Dan Feist said:

 

Mmm, Pherhaps I'll have to quiz mixergy a bit more on exactly how different their tank is/isn't from a discharge/mixing perspective is., Unless @Robert Clark or @joth know?

 

All I can say is with no hot water being heated overnight, is the morning hot water is still plenty hot.  It may have lost a few degrees in the tank, and there is no doubt less of it, but it has not gone all luke warm.

[Dan F]

27 minutes ago, ProDave said:

All I can say is with no hot water being heated overnight, is the morning hot water is still plenty hot.  It may have lost a few degrees in the tank, and there is no doubt less of it, but it has not gone all luke warm.

 

I found some data which would back up both your assertion and Mixergy's claim.  Standard tank doesn't mean all water mixes, just that more mixes, but there is still hot water at top.

 

https://ec.europa.eu/environment/ecoap/sites/ecoap_stayconnected/files/etv/mixergy_verification_report_npl_08122016_-_no_appendices.pdf

 

 

 

 

 

 

 

[joth]

20 hours ago, Dan Feist said:

I found some data which would back up both your assertion and Mixergy's claim.  Standard tank doesn't mean all water mixes, just that more mixes, but there is still hot water at top.

 

https://ec.europa.eu/environment/ecoap/sites/ecoap_stayconnected/files/etv/mixergy_verification_report_npl_08122016_-_no_appendices.pdf

 

That report is interesting, as it shows that a standard tank's usable volume decreases as the flow rate increases (as expected, more turbulance results in loss of the thermocline), whereas the Mixergy actually has a slight increase  in usable volume as the flow rate increases. Any idea why?

 

 

 

 

On 13/04/2020 at 18:35, Dan Feist said:

 

Mixergy uses Newark tanks, what I'm not sure is if they use the standard Newark inlet diffuser, or if they use a custom diffuser or are doing anything else on top of this.

 

 

Couple interesting points on this from the report:

- It states: "The Mixergy Tank is a hot water tank that makes use of a novel inlet diffuser and angled heating element scheme to increase the utilisation of stored water within a domestic hot water tank"

- It seems they used a Newark tank as the reference "standard" tank (going on Table 7 & 8) so does make a direct comparison of the two

- The tests were carried out by Newark on their premises (but under instruction of NPL), so not entire independent, but  sure what more to read into that if anything.

[Dan F]

Quote

whereas the Mixergy actually has a slight increase  in usable volume as the flow rate increases. Any idea why?

 

No idea, it could just variance in test.  Kind of a shame they tested with 75L and not a larger tank, but I guess the the same model applies.  If anything I'd assume large tank might be slightly better as the size of the inlet difussor will be smaller compared to the total volume or the tank and further from the hot water at the top (that's guesswork though..)

[Tom]

13 hours ago, Dan Feist said:

 

No idea, it could just variance in test.

 

Yep, looks like it. If you look at the error bars the upward tick at 15kg/min is not statistically significant

[BristolBill]

On 13/04/2020 at 15:09, Dan Feist said:

Has anyone installed and is using a Mixergy tank? @Robert Clark what did you do in the end?

 

We are very keen to avoid a standard UVC as we won't have a gas supply and beleive that load-shifting DHW electricity demand makes a ton of sense in both winter (from cheap nightime tarriff) but also in the summer (from free PV during the middle of the day).  My understanding is that with a standad UVC this is a major challenge without reheating water in the tank as you use it, unless you want lukewarm showers.

 

Using Sunamp heat batteries is a great way to achieve i) load-shifting ii) partial charging iii) low heat-loss and all nice and compart but we've been advised that in order to get a very good flow rate and >300L capacity we'd be looking at 2 x UniQ9, and that's where Sunamp becomes less interesting because we'd be looking at almost £5000!

 

It's clear that Mixergy is not as compact as a Sunamp (not a major issue for us), and will never be able to compete on heat-loss, but it does support load-shiting and partial charging and costs less that a 1/3 of the price of 2 x UniQ9.  So, I'm really wondering if it makes any sense an extra £3,000 on Sunamps.  (I know some people will mention the G3 annual service but in reality very few people pay yearly for this service unless pherhaphs they are landlords).

 

Mixergy shared some real-world data from current installs that shows how a tank with 25% "charge", still has 58C temperature at the top, while bottom is at 12C, so it's definitly more than just marketing and an app.  Also, looks like it potentially has better control system than Sunamp with option to use their app or integrated directly via modbus.

 

Thoughts?

 

 

Yes.  A 180l tank with an indirect coil and a PV element hooked up to an Eddi diverter.  Had there been the space without knocking quite a few things around I'd have gone for a larger tank.  That being said I have only been in trouble for a bath running cold once.

 

We've used it in a few ways and am slowly refining what the lasting solutions will be.  The following will be too interventionist for many and for me too in the longer term but right now I'm experimenting.

 

First: Electrically heated only, after had made the wondrous decision that hot water and no heating was a suitable time to move back into a building site.  No smart meter and thus no cheap rate at this point so, rather than heating a full tank, by checking the hot water contents indicator you could see if you had enough for the next draw.  I do not recommend living this way but then we also had an 8m2 hole in the back of the house at the time so..

 

Second: Electrically heated overnight on Octopus Go tariff, typically to 100%.  Set to maintain min 20 max 40% via the indirect coil through the expensive electric part of the day if we got down this far.  Upped this to 50% after a few 'complaints'. The ability to select which sources should be used at which times is useful here.  So if I see the tank is at 30% and want more for a longer shower I can press the button to select the desired percentage (in increments of 10).  It will then trigger the heat source I have said should be used for that time period.

 

Thirdly: Baby 2 imminent and thus hot water not being immediately available wasn't a player,  Solution: Look at the weather forecast for the next day and either set it to charge to 100% overnight on the cheap rate or let the sun do its thing or a mixture of the two.  Fortunately March and April this year were atypical British weather months so all well. 

 

Clearly it doesn't have the heat loss characteristics of the Sunamp but it does let you know where you stand with hot water availability and has a host of available measurements and options.

 

Happy to answer any questions (if I know the answers) but please accept my apologies for any delay as a newborn is running the show.