Vaillant high(er) temperature ASHP?

[Ed Davies]

1 hour ago, Dreadnaught said:

Interestingly, R290 seems to be simply just propane gas (!)

 

It seems to be a mixture of propane and isobutane.

[Dan F]

@Dreadnaught Undecided as of yet.  

 

The efficency is only 5-10% better than LG/Samsung R32 models, so it will likely come down to price/availability if we are using a UVC. (the COP of 5.4 is a bit of an outlier with specific models at specific temperatures) 

 

That said, this ASHP would defintily allow the use of Sunamp PCM58 without worrying about if it meets the required flow temperatures in practice and if it is still able to charge Sunamp at low outside temperatues.  (this is a concern with R32 models without Sunamp doing testing and I know others including @oranjeboom and @joth are wary about using ASHP with Sunamp due to this)

 

From an effiency standpoint, it might be prefferable to use a Sunamp PCM48 (which they say they plan to release) as this is hot enough for DHW, gives better COP and wouldn't require a speciifc ASHP.  The downside of PCM48 is that you get les showers per Sunamp.

 

In sumary, I'm waiting to see fulls spec, and also waiting to see what Sunamp release (if anything) in the next 4-5 months.

Edited February 5, 2020 by Dan Feist

[oranjeboom]

39 minutes ago, Dan Feist said:

From an effiency standpoint, it might be prefferable to use a Sunamp PCM48

 

And what of costs of that PCM over the standard PCM58? And availability? 

 

41 minutes ago, Dan Feist said:

The downside of PCM48 is that you get les showers per Sunamp.

 

So you would need larger PCM48 units then = more required space, and the units may cost more also? May be okay if your DHW demand is low I guess.

[joth]

1 hour ago, Dan Feist said:

The efficency is only 5-10% better than LG/Samsung R32 models, so it will likely come down to price/availability if we are using a UVC. (the COP of 5.4 is a bit of an outlier with specific models at specific temperatures) 

 

 

Yeah note that model is 3-phase too! Single phase only takes you to 7kW in their range, very surprised by that (having just committed to sticking with single phase).

 

Daikin have units are very readily available and claim an much better A7/W35 COP of 5.75 comparing like for like 7kW models, so the R290 super coolant achieving 4.8 is bit of a let down in that regard

If I believe that claim, then on PHPP (even allowing for Sunamp being twice as good on heat losses) it means we're much better off with UVC + Daikin than Sunamp+Vaillant R290, both in terms of capital and running costs. The only linger temptations for Sunamp then is less summer overheating and smaller size, and the Vaillant R290 maybe marginally quieter running, but I don't think either those points justify the massive increase in costs and risks (not to mention, installers of either Vaillant ASHP or Sunamp are like hens teeth in our area, getting someone with experience of both is impossible).

 

The one fly in the ointment for me is Daikin seem to have discontinued the monobloc model with cooling (EBLQ07CAV3), whereas the non-cooling version is readily available everywhere :-(  If I can source the EBLQ on the continent I literally might drive over there to get it. Need to check how big the box for it is! 

 

PS thanks for pursuing and sharing all this info @Dan Feist.  My efforts achieved 100% less data, not for want of trying!

 

 

 

Edited February 5, 2020 by joth

[Dan F]

12 minutes ago, joth said:

The Daikin units are very readily available and claim an even better A7/W35 COP of 5.75,

 

Not sure how to interept Daikin numbers, as it looks like they quote a COP of 4.27 for 55C flow temperature.  Can this be right, seems too good!

(See: Average climate water outlet 55°C - C Condition (7°CDB/6°CWB))

 

13 minutes ago, joth said:

The one fly in the ointment for me is Daikin seem to have discontinued the monobloc model with cooling (EBLQ07CAV3), whereas the non-cooling version is readily available everywhere ?

 

Colling is must for us. Wondering if cooling could be enabled somehow on non-cooling version.

[joth]

7 hours ago, Dan Feist said:

7 hours ago, joth said:

The one fly in the ointment for me is Daikin seem to have discontinued the monobloc model with cooling (EBLQ07CAV3), whereas the non-cooling version is readily available everywhere ?

 

Colling is must for us. Wondering if cooling could be enabled somehow on non-cooling version.

 

Right. I'm very reluctant to put down £2k+ on something that doesn't have it and then regret it.

 

7 hours ago, Dan Feist said:

Not sure how to interept Daikin numbers, as it looks like they quote a COP of 4.27 for 55C flow temperature.  Can this be right, seems too good!

(See: Average climate water outlet 55°C - C Condition (7°CDB/6°CWB))

 

 

I'm getting more and more suspecious of that table (or, my interpretation of it). 

I found this shop selling the EBLQ (reversable) model online in France. At first I thought "yay short hop to go get it" but then I noticed in their COP table they list A7/W35 as 4.52 for the 7kW model.  Which matches the "COP" row at the very top of this page: https://www.daikin.ch/fr_ch/products/EBLQ-CV3.table.htm

4.52 (1), 3.42 (2)

 

The big table at the bottom of that page is listed as "COPd" values, not COP. Along with a bunch of other value (Cdh, Pdh, losses) I'm not sure how to interpret either.  So yes, false alert I think,

 

 

[Dan F]

Three single-phase variants of this new R290 ASHP have now been MCS-certified and can be found in MCS  database.

 

The 12KW version seems to have pretty impressive SCOP values:  3.5@55C and 4.9@35C.  Not sure why 65C values aren't included here, I've requested more technical details.

 

Maybe I should reconsider Sunamp, now there is a monobloc ASHP can than happily charge a 58PCM Sunamp without requiring compatability testing or a backup heater.  I do want to check COP and flow rates at 65C first though..

 

 @joth@oranjeboom

 

Also, Sunamp have all but confirmed that there is no PCM48 version that will be avialable in the next 6mths, but to expect an annoncment regarding PCM43.  I'm not sure PCM43 is really suitable for DHW though, flow rate must be closer to 40C max + pipe losses != a very hot shower.  Also 25% less dense than PCM58 I assume.

 

Edited March 10, 2020 by Dan Feist

[joth]

Looking through the COP figures I'm a little underwhelmed by it, tbh

On the 7kW model I see A7/W35 COP of 2.8, which is actually lower than the A7/W55 score (2.9). The higher power units fair even worse at low flow temperatures (COP=2.4).

Compared to the 4.52 on the Panasonic monobloc we've currently selected, I'm not sure if the improved DHW performance (with addition of a Sunamp) justifies this kind of hit in heating.

EDIT: ignore all that. I was mixing up A-7/35 with A7/W35 due to very unfortunate word wrapping in their spec sheet. A7/W35 COP is 4.8 so much closer to what I expected!

 

I'll put it through PHPP later and compare. 

 

Lower GWP is obviously nice idea. But the main issue I've had is exactly zero of the Vaillant installers will talk to me. The only returned calls/emails were to say we're out of their service area (by, like, 10miles). 

 

Many thanks again @Dan Feist for sharing this info though. You really got some better contacts there than my attempts managed!

 

 

 

 

Edited March 12, 2020 by joth

[Dreadnaught]

1 hour ago, joth said:

On the 7kW model I see A7/W35 COP of 2.8

 

I think you're reading the line for A-7/W35, which is 2.8. (Notice the minus sign.)

 

The coefficient of performance for A7/W35 is 4.8, slightly better than your Panasonic monobloc (4.52).

 

Edit: you saw it before I commented. Ignore this. Mods please delete.

 

Edited March 12, 2020 by Dreadnaught

[joth]

3 hours ago, Dreadnaught said:

The coefficient of performance for A7/W35 is 4.8, slightly better than your Panasonic monobloc (4.52).

 

Right yes it was early in the morning and I not enough coffee yet. I realize now I'd already found the 4.8 figure last month and commented on that upthread, and indeed already done the PHPP experiment too. The new UK spec matches the one previously published on the vaillant.nl website so same findings hold: we'd save 1.5kWh/(m2.a) on PER so about 227kWh/a or £35/a having this ASHP vs the Panasonic. (And discount the Daikin as both uncredible, and no cooling), and a bit more ontop from having lower heat losses of the Sunamp.

Add on top there's going to be a delay until Sunamp have tested this new heatpump to certify its use, plus installer availability is so limited, I am leaning towards whatever presents itself as the most trustworthy/reliable option but still open minded it could be this setup.

 

[Dan F]

@joth In theory you also save on (minimal) costs associated with legionella cycle, as the ASHP can do this instead of an immersion heater.

 

I personally, don't see any reason Sunamp would need to test this ASHP given specs.  Testing was/is much more important for other models with lower max temperatures and reduced operating ranges (can't heat to 65C below 2C for example), but this one shouldn't really need testing.

 

I'm personally still not convined about using Sunamp with ASHP yet though, even though this model does reduce the risk of ASHP compatabiity significantly:

- Lower COP's to charge Sunamp vs. heating UVC to 55C.

- Harder (or not possible?) to leave room in Sunamp for PV diversion, than with a UVC where you can heat to 55C and then allow PV to heat further.

 

 

Edited March 12, 2020 by Dan Feist

[Jeremy Harris]

Not sure there's any useful reason for running an anti-legionella cycle on a closed hot water system, as there is no opportunity for a primarily droplet/airborne pathogen like legionella to get into the pipework or tank, plus the residual disinfection from water treatment should mean that the water entering the house is bug free (that's a statutory requirement in the water quality standard).

[joth]

@Dan Feist when I spoke with Sunamp they were adamant their own testing would be needed due to control systems (in)compatibility catching them out repeatedly with so many other ASHPs. I think I mentioned at the time they could just as well test with an existing Vaillant aroTherm ASHP as surely the control logic would be pretty similar.

 

Agree with the other points. I personally don't care tooo much about the cost implicartions of a legionalla cycle. Between PV eliminating it in summer and an occasional blast in winter (or not, per other views on here) we're talking about pennies really. The hassle of getting formal G3 maintenance once a year is more of a motivation to go Sunamp, plus space saving, but offset by the lack of long-term reliability evidence. I'll probably continue to prevaricate and make a panic decision in a few months based on which suppliers actually want to talk to me at that point.

 

[Dreadnaught]

Miles off topic.@joth I think I recognise Half Dome in Yosemite as your avatar. Been up it?

[Dan F]

15 minutes ago, joth said:

The hassle of getting formal G3 maintenance once a year is

 

Does anyone actually do this, or this is just Sunamp sales argument?  I don't think they do do they...

[arg]

34 minutes ago, Dan Feist said:

- Harder (or not possible?) to leave room in Sunamp for PV diversion, than with a UVC where you can heat to 55C and then allow PV to heat further.

 

Surely you'd still want to divert the PV into the ASHP rather than diverting it to reisistance heating, in order to get more bang for your buck?

 

I suppose there's edge cases like high summer when the ASHP is too busy cooling, or wanting to trickle it in when the PV is generating less than the minimum needed to run the ASHP compressor,.  In the latter case using resistance heating is only a win if you have low PV output for hours on end - if it's winter time and you aren't going to have enough anyhow, might as well run the HP on half PV half grid power (if you are getting COP of 2, that ends up using grid power for 1/4 of the total heat input,), and in summer time there are probably enough hours where the PV is generating enough to run the HP to get the job done.

 

Daikin at least has modes for limiting the ASHP consumption for this sort of purpose (only a couple of bands, not fine-grain control).  Not sure if Valliant does similar.

[Dan F]

4 minutes ago, arg said:

Surely you'd still want to divert the PV into the ASHP rather than diverting it to reisistance heating, in order to get more bang for your buck?

It your UVC is already at 55C, and you have a low-temp ASHP this isn't very feasible and that's why most people would switch to immersion for PV diversion.  This Valliant ASHP goes up to 75C, so this might be possible, but I'm not sure how you'd wire things up to achieve this.

 

4 minutes ago, arg said:

I suppose there's edge cases like high summer when the ASHP is too busy cooling

That's a good point. 

 

Getting more bang-for-your-buck isn't very important in the summer if you have a fair amount of PV.  But in spring/autumn would mean your PV would go twice as far, and in winter it would mean cheap night-time electricitiy import would potentially algo go twice as far.

Edited March 12, 2020 by Dan Feist

[Jeremy Harris]

6 minutes ago, arg said:

 

Surely you'd still want to divert the PV into the ASHP rather than diverting it to reisistance heating, in order to get more bang for your buck?

 

I suppose there's edge cases like high summer when the ASHP is too busy cooling, or wanting to trickle it in when the PV is generating less than the minimum needed to run the ASHP compressor,.  In the latter case using resistance heating is only a win if you have low PV output for hours on end - if it's winter time and you aren't going to have enough anyhow, might as well run the HP on half PV half grid power (if you are getting COP of 2, that ends up using grid power for 1/4 of the total heat input,), and in summer time there are probably enough hours where the PV is generating enough to run the HP to get the job done.

 

Daikin at least has modes for limiting the ASHP consumption for this sort of purpose (only a couple of bands, not fine-grain control).  Not sure if Valliant does similar.

 

 

Pretty hard to positively divert PV excess generation to an ASHP in practice, as both the PV output and the ASHP demand vary a lot, and the ASHP tends to go up and down a lot as it modulates.  I'm not aware of any ASHP that will accept a variable power input of the type delivered by the majority of PV diverter units. 

 

Controlling resistance heating is a great deal easier, as it generally doesn't care too much about the way it's being fed with power.  In practice I've found that just using  a pretty simple "energy bucket" type excess PV generation diverter provides most of our hot water throughout the year.  The cost of our hot water (the part we pay for) is about £30 per person per year, so there's not a lot of incentive to invest in something more complex in order to reduce that bill further.

[arg]

I was assuming you'd do something like:

• When PV generation is predicted to be good (summer) and/or your store is fairly full, run the HP only if there's enough excess to cover the whole expected power draw.
• When generation is predicted to be poor, run the HP as soon as there's any reasonable amount of PV and top up with grid power - on the basis that you are going to have to use grid power when the sun's gone down if there isn't enough hot water in your tank at that point.
• If you've got something like the Daikin unit (which has 4 configurable power levels controlled by external inputs, corresponding consumption configured in 1A steps), then you can track rather closer, but obviously not as close as something with proportional control.  Still, if for example you've set it up for 4 equal steps and you have a COP of at least 2, as soon as you are over the first step to let you turn it on you are then you are automatically winning compared to the resistance heating - the proportional resistance heater could use up the balance between actual generation and the next step of your power control, but the HP is putting out more heat even with that bit "thrown away".

As ever with these things, it does depend what you are trying to optimise - overall energy consumption, running cost,  initial cost, independence etc.   And it also depends what would happen to the excess generation if you can't follow it exactly - the FIT-with-deemed-export, the paid-a-small-amount-for-export, or the store-in-a-battery scenarios give a different level of imperative to closely follow the generation.

Edited March 12, 2020 by arg
missing sentence

[ProDave]

9 minutes ago, arg said:

I was assuming you'd do something like:

• When PV generation is predicted to be good (summer) and/or your store is fairly full, run the HP only if there's enough excess to cover the whole expected power draw.
• When generation is predicted to be poor, run the HP as soon as there's any reasonable amount of PV and top up with grid power - on the basis that you are going to have to use grid power when the sun's gone down if there isn't enough hot water in your tank at that point.
• If you've got something like the Daikin unit (which has 4 configurable power levels controlled by external inputs, corresponding consumption configured in 1A steps), then you can track rather closer, but obviously not as close as something with proportional control.  Still, if for example you've set it up for 4 equal steps and you have a COP of at least 2, as soon as you are over the first step to let you turn it on you are then you are automatically winning compared to the resistance heating - the proportional resistance heater could use up the balance between actual generation and the next step of your power control

As ever with these things, it does depend what you are trying to optimise - overall energy consumption, running cost,  initial cost, independence etc.   And it also depends what would happen to the excess generation if you can't follow it exactly - the FIT-with-deemed-export, the paid-a-small-amount-for-export, or the store-in-a-battery scenarios give a different level of imperative to closely follow the generation.

The best I do is time the DHW to not come on until mid morning when there is a reasonable chance of decent PV veneration to power some or all of it.

 

Only one of us showers in the morning, and we rely on HW from last night for that.

[Nick Laslett]

On 12/03/2020 at 20:38, Jeremy Harris said:

 

 

Pretty hard to positively divert PV excess generation to an ASHP in practice, as both the PV output and the ASHP demand vary a lot, and the ASHP tends to go up and down a lot as it modulates.  I'm not aware of any ASHP that will accept a variable power input of the type delivered by the majority of PV diverter units. 

 

 

Maybe I'm misunderstanding this statement. I assumed my PV in the summer would power the ASHP in cooling mode. Is that not the case? 

[Nickfromwales]

3 minutes ago, Nick Laslett said:

 

Maybe I'm misunderstanding this statement. I assumed my PV in the summer would power the ASHP in cooling mode. Is that not the case? 

If it's injected straight into the CU and not delivered through a diverter the PV will power anything and everything, when generation is sufficient of course.

[Nick Laslett]

11 minutes ago, Nickfromwales said:

If it's injected straight into the CU and not delivered through a diverter the PV will power anything and everything, when generation is sufficient of course.

 

I assumed it worked exactly as you described. Does fitting something like a MyEnergi Eddi, make this more difficult?

[Nickfromwales]

The Eddi is very versatile and a great bit of kit. It'll do most of what anyone would want / need. You would need to look at the minimum thresholds for diverting power, but, IIRC, the Eddi will do this proportionately.

The equation can only be answered by knowing how much PV you have, it's expected yield, and what consumption ( and when ) you intend to offset or manage with a diverter. There is no quick answer I'm afraid.

Excess can very easily be be diverted to hot water, for eg, but the ASHP needs access to power 24/7 normally so would just rely on taking that direct from the CU. As it's a multiplier, it's running costs are negligible and therefore rarely the focus of diversion per se.  

[Nick Laslett]

1 minute ago, Nickfromwales said:

The Eddi is very versatile and a great bit of kit. It'll do most of what anyone would want / need. You would need to look at the minimum thresholds for diverting power, but, IIRC, the Eddi will do this proportionately.

The equation can only be answered by knowing how much PV you have, it's expected yield, and what consumption ( and when ) you intend to offset or manage with a diverter. There is no quick answer I'm afraid.

Excess can very easily be be diverted to hot water, for eg, but the ASHP needs access to power 24/7 normally so would just rely on taking that direct from the CU. As it's a multiplier, it's running costs are negligible and therefore rarely the focus of diversion per se.  

 Thank you for the clarifications. Makes more sense now.