Modulation % of Riello

[Post and beam]

I have been drawn to considering  a Riello 6kw heat pump. Possibly 8kw. Looking at the documentation and remembering that modulation is important i see that they modulate to 40%. 

From what i have learnt here modulation to a 'low' value is considered important. So is 40% acceptable?

What other factors might mitigate this.

The units look to have a good Scop and price which was the reason for looking at them.

[JohnMo]

I believe the Riello are rebadged Midea units, so you could look there to compare pricing.  They have the same controller, same casing, same manual rebadged. Also check the outputs as the name plate kW seems to be the min output rather than max.  Good modulation, but could be

 

Freedom Heat Pump quoted me £2.3k plus VAT for 4kW one.  But also sure both Riello and Midea units on eBay for less than £2k, but they were too big for me.

 

Was high on my contender list, modulation looks as good as most other heat pumps.

[Post and beam]

5 minutes ago, JohnMo said:

looks as good as most other heat pumps

Thats good to know. At least they publish theirs. I could not find the figure for Samsung of similar size. The 'end of line' samsungs also look to be very good prices. And, as i have been informed on here before now 'Get a Samsung you wont go wrong'

[sharpener]

2 hours ago, Post and beam said:

The 'end of line' samsungs also look to be very good prices. And, as i have been informed on here before now 'Get a Samsung you wont go wrong'

 

IIRC @markocosic says they achieve their turn-down ratio by using hot gas bypass which knackers the CoP.

[JamesPa]

3 minutes ago, sharpener said:

 

IIRC @markocosic says they achieve their turn-down ratio by using hot gas bypass which knackers the CoP.

I spotted this.  The internal piping diagram shows that it does have hot gat bypass.  The question, which I don't believe has been answered, is the hot gas bypass there to extend an otherwise respectable modulation ratio (in which case its arguably OK) or is it there because, without it, the modulation ratio is poor (in which case its definitely not OK).  Maybe @markocosic knows.  Some part load figures for Samsung would help, but so far I haven't seen any.

[Post and beam]

Apologies, are we talking about the Riello or the Samsung now?

[sharpener]

1 hour ago, sharpener said:

 

IIRC @markocosic says they achieve their turn-down ratio by using hot gas bypass which knackers the CoP.

 

"they" is Samsung

 

re the OP, Good Energy quotes are based on Midea FWIW so I imagine they are not rubbish.

 

Edited July 24, 2023 by sharpener

[Post and beam]

1 hour ago, sharpener said:

"they" is Samsung

Thanks dude

[sharpener]

3 hours ago, JamesPa said:

The question, which I don't believe has been answered, is the hot gas bypass there to extend an otherwise respectable modulation ratio (in which case its arguably OK) or is it there because, without it, the modulation ratio is poor (in which case its definitely not OK).  Maybe @markocosic knows.  Some part load figures for Samsung would help, but so far I haven't seen any.

 

Surely they would not add the mechanical complication unless it was necessary for some performance reason like achieving a reasonable turndown ratio - which may still be uncompetitive so they don't publish it.

 

Hopefully @markocosic will be along to tell us, if he is not on holiday.

[JamesPa]

2 hours ago, sharpener said:

 

Surely they would not add the mechanical complication unless it was necessary for some performance reason like achieving a reasonable turndown ratio - which may still be uncompetitive so they don't publish it.

 

Hopefully @markocosic will be along to tell us, if he is not on holiday.

They might add it to stop flow/temp errors either end of the season.  It probably doesn't cost much, is a well known technique, and anything which avoids call outs is good.  Alternatively their compressor modulation might be rubbish.

[DanDee]

8 hours ago, sharpener said:

 

IIRC @markocosic says they achieve their turn-down ratio by using hot gas bypass which knackers the CoP.

 

 

The Samsung old EHS range does not have any hot gas bypass/EVI injection, it's pure compressor horse power.

 

 

 

The new HT quiet borrowed tech from the big old commercial units, but the hot gas bypass on the Samsung we are talking about should not be confused with the original hot gas bypass and their function on the chillers that used them due to non inverter compressors. In Samsung it has a pressure protection role.

 

 

 

 

 

 

 

 

 

 

On keymark site you can see some data with lower capacity temps, but not what you are looking for.

 

https://keymark.eu/en/products/heatpumps/certified-products

 

HT quiet 8kW

 

 

 

 

 

 

Edited July 24, 2023 by DanDee

[Beelbeebub]

What is the bivalent temperature? I've seen it a few times.

[DanDee]

14 minutes ago, Beelbeebub said:

What is the bivalent temperature? I've seen it a few times.

http://www.gorenje.com/heating-systems/en/heat-pumps/heat-pumps-aerogor/bivalent-systems

 

Humm I found some product fiche from Greece and the COP is lower than Keymark(correction it's the 55C only in the fiche)

 

https://www.ambientclima.gr/wp-content/uploads/2022/11/common-energylabel-ae080bxydeg-eu-ecodesign.pdf

 

https://www.ambientclima.gr/wp-content/uploads/2022/11/common-energylabel-ae120bxydeg-eu-ecodesign.pdf

 

https://www.ambientclima.gr/wp-content/uploads/2022/11/common-energylabel-ae140bxydeg-eu-ecodesign.pdf

 

The lowest output at 12C is 4kW for the 8 and 4.7kW for 12/14 due to the bigger evaporator

Edited July 24, 2023 by DanDee

[markocosic]

1 hour ago, DanDee said:

The new HT quiet borrowed tech from the big old commercial units, but the hot gas bypass on the Samsung we are talking about should not be confused with the original hot gas bypass and their function on the chillers that used them due to non inverter compressors. In Samsung it has a pressure protection role.

 

Great explanation @DanDee

 

That keymark page DOES kinda have the information that you're looking for on the 8 kW plated (but in reality more like a unit that would otherwise delivery say 12 kW at certain ambient temperatures but is capped in software to only deliver 8 kW) R32 Samsung EHS Mono HT. I'm led to believe that the minimum turndown is indeed 4 kW on those. Can operate below this but not without an efficiency hit. One of the Samsung tech chaps strongly hinted at the hot gas bypass being required to do that when delivering heat at lower temperatures.

 

If you look at the Vaillants you'll find that the bigger units (with higher compression ratio scroll compressors and higher sCOPs at the higher temperatures)  do better than the smaller units (lower compression ratio rotary compressors) but their turndown isn't anywhere close to as good. 

 

The Gen6 Samsungs were rotary compressors. What's the lowest listed output on those?

 

 

"End of line" pricing might look good. Don't forget all the extra control gubbins that you'll need (needs a special box if not using Samsung cylinders) and ask yourself how they they perform over say 10 years. Might not be worth the saving if they use an extra £1k in electricity over their life?

 

e.g. Basic Samsung G6 that looks a bargain immediately becomes £1866+vat once you add the controller:

https://www.theheatpumpwarehouse.co.uk/shop/heat-pumps/air-source-heat-pumps/samsung-5kw-r32-monobloc-air-source-heat-pump/

 

£2124+vat (though check ratings - the nameplate has little to do with the actual capacity on many units)

https://www.theheatpumpwarehouse.co.uk/shop/heat-pumps/air-source-heat-pumps/riello-6kw-monobloc-air-source-heat-pump-nxhm-006/

 

£3000+vat

https://www.theheatpumpwarehouse.co.uk/shop/heat-pumps/air-source-heat-pumps/vaillant-arotherm-plus-5kw/

 

 

Find some cycles on here and compare sCOPs for the cycles of interest:

https://heatpumpmonitor.org/

 

e.g.

 

Here's one unit last week reheating a hot water tank. COP 2.5 for the cycle.

 

 

And another. 3.change for the cycle:

 

Another. COP4

 

 

And here's another. COP 4.8 for the cycle.

 

@puntloos that's one Samsung, one Mitsibishi one Daikin one Vaillant FWIW. The worst costs less than half what an immersion does. The best costs less than a quarter. Depends as much on the install detail as the heat pump itself.

 

Space heating will more closely follow the "book" sCOP if it's reasonably weather compensated/continuous.

[JohnMo]

23 minutes ago, markocosic said:

Find some cycles on here and compare sCOPs for the cycles of interest:

Some comments

 

The last curve it was circa 20 degs outside compared to the others circa 15, so CoP should be better. The last one is also heating to a lower temp not going above 55 before cutting out, while the others are hitting close to 60.

 

The first HP is heating cylinder in 35, second one 40, third one 90, the last 70 mins.

 

Way to many variables to pin anything statistical against. You could say the coil size in the cylinder or set point it is being heated is also something that needs to be compared. None of that data is represented.

 

Rubbish in rubbish statistics at its best. Makes good headlines though

[markocosic]

7 hours ago, JohnMo said:

Way to many variables to pin anything statistical against. You could say the coil size in the cylinder or set point it is being heated is also something that needs to be compared. None of that data is represented.

 

Yes.

 

"It's about the install detail as much as the heat pump itself"

 

They were all from last week.

 

Can conclude that it's stupid to reheat cylinders first thing in the morning vs middle of the day. 

 

Can conclude that it's stupid to heat quickly.

 

Can conclude that it's stupid to heat them too hot etc.

 

By a factor two.

 

Some of that week be down to installer/user error. Some down to control available on the unit. Some down to clagging A N Other cylinder onto the heat pump and having only flat out or nothing control available.

 

What are the options available to those buying end of line Samsung units with the control interface to a third party cylinder?

 

Those buying Samsung units with the Samsung tank? Ditto other models.

 

The point was perhaps don't cost yourself more than you save over the life of the asset.

 

Space heat will follow the listed sCOP if output temperature is vaguely compensated. Hot water sCOP isn't listed and varies significantly between setups.

[Beelbeebub]

One outcome of this is a universal standard HP interface would be useful.

 

The proprietary control box costs just under a quarter of the price of the physical unit.

 

The good news is that these "fire sale" Samsung units prob sky indicate how much HPs could be sold for regularly.  The current 4k for a 5/6kw unit average seems to be a combination of demand and the fact these units are fairly new, there's lots of R&D and setup cost to be amortized.  Vaillant have spent £4m on upgrading and expanding its.uk factory and £55m on its.german r&d plant.

 

Hopefully, as more competition comes on the market and volumes (and supply channels) increase the cost will start to drive down. 

[JohnMo]

7 minutes ago, Beelbeebub said:

Hopefully, as more competition comes on the market and volumes (and supply channels) increase the cost will start to drive down. 

You still don't seem to grasp that there are millions of ASHP made each year and many millions of A2A worldwide. The inverter driven heat pump has been about for well over a decade, maybe 2.

 

The first heat pumps were in people's homes a century ago. Nothing new, nothing rocket science about a heat pump. It's a simple refrigerator cycle with a heat exchange to water.

[markocosic]

There isn't much that needs standardising.

 

They're ALL going to need underfloor, radiators, or fan coils (to suit the use case)

They're ALL going to need a cylinder with a top to bottom coil, a thermal store with a freshwater module on it, or a plate loaded cylinder (also to suit the use case)

 

£3000 is a sensible figure for heat pump and appropriate hot water provision for a modest house.

 

 

 

I've just purchased one of these for the cabin build.

 

https://airway.lt/preke/midea-xtreme-save-26-293-kw/

€600 inc 21% VAT for the "standard" range

 

https://orostudija.lt/silumos-siurbliai/midea-silumos-siurbliai/oro-kondicionierius-midea-xtreme-save-eco-09

€450 inc 21% VAT for the "false economy" range

 

 

Monoblocs involve materially more material though. They're larger capacity. They've plate heat exchangers and pumps. They're in need of electric heaters for frost protection. Even just delivering the things is a significant expense as they're not 30 kg lumps in a cardboard box any more.

 

 

Part of me does wonder if we'll see "plug and play" propane splits with little indoor modules. "MrCool" style precharged linseets etc. Those could easily be 30 kg appliances in cardboard boxes and no harm done if they're propane fill.

 

[Beelbeebub]

38 minutes ago, JohnMo said:

You still don't seem to grasp that there are millions of ASHP made each year and many millions of A2A worldwide. The inverter driven heat pump has been about for well over a decade, maybe 2.

 

The first heat pumps were in people's homes a century ago. Nothing new, nothing rocket science about a heat pump. It's a simple refrigerator cycle with a heat exchange to water.

I know millions of a2a sets are made and fitted each year. Mostly for cooling (globally the biggest use).

 

If the UK were minded to go the a2a route (as I believe France are) then we could absolutely tap into that market.

 

As @markocosicsays, it would massively improve the logistics.  If r290 splits were allowed for home DIY then it would make the cost of installation much lower. If a r290 to water invented cylinder could be made readily available it would solve the dhw issue. The only other hurdle would be interoperability between brands.

 

.The *only* issue with r290 is the flammability - admittedly a pretty big issue!

 

I beleve china and India have been using mini and multisplit r290's for over a decade. Be good to see what the safety record is.

 

But in the UK we (currently) prefer air to water which, as has been pointed out, have more stuff in them and globally, the volumes are small Vs a2a type units. To be honest they are a suboptimal solution, except maybe when it comes to underfloor heating (but that could easily be solved with a r290 to water PHX/manifold/pump unit) but it is where we are.

 

One potential option for my upgrade path is getting an F-Gas cert and fitting a2a units.  My one reservation with a2a is the long term spare parts/interoperability issue. If one of my head units plays up in 7years time can I get a drop in replacement easily?  With water based systems it's easy. 

 

Edit: side thought. The big issue with r290 is the flammability, but we already accept a far higher potential source of flammable gas in the home. The issue as I understand it, is that main gas has an odour chemical added so any leak is deemed to be easily detectable far below dangerous levels. It is currently impossible to use that chemical in the refrigerant circuit. If that hurdle could be cracked why would having an r290 unit in the home be any different from the canister of lighter gas or mini camping stove in the house and why would a DIY fill be any different from changing your BBQ cylinder?

Edited July 25, 2023 by Beelbeebub

[billt]

The other difference with propane is that it's denser than air so accumulates in sumps and drains and doesn't disperse as easily as mains gas.

[Beelbeebub]

20 minutes ago, billt said:

The other difference with propane is that it's denser than air so accumulates in sumps and drains and doesn't disperse as easily as mains gas.

Ah good point! But an odor chemical would make things alot safer, and the quantities are pretty small, basically 2 or 3 plumbers blowtorch cylinders.

 

I feel careful monitoring for leaks in the unit by looking at temp, pressure and compressor load, could alert the user would mitigate the risk. Maybe even portable gas detectors located on the floor similar to CO2 and smoke alarms.

 

Leaks would mostly come from bad joints and could be mitigated by premade "pushfit" connectors only, no DIY onsite brazing, and damage (surface mounted pipework or armoured and vented trunking).

 

Very small leaks (mg per day) are unlikely to cause any danger except in a very sealed space (say a wall cavity).  Larger leaks only cause a (relatively) short term danger window before even a heavier than air gas disperses through natural currents.

[markocosic]

Propane could go boom.

 

The EU is on track to allow 0.9 kg of propane in resi split systems. The various F-Gas based unions are seeking to delay this. Restrictions on who can buy / use F-Gas splits keeps them in a job.

 

The risk is minor. Most leaks would be small and dissipate. Certainly minor vs the 2x 15 kg propane cylinders in "calor gas heaters" that you're permitted to keep indoors today.

 

If it were a problem you'd vent the installation to atmosphere (fridge lines in ducts; all joints within enclosures; vented to an outdoor space) but they're not even asking that in the proposed regs.

 

It'll be a fun space.

 

Joints won't be pushfit with propane. They'll be flared and screwed. It's under decent pressure in a fridge system.

 

As to spares...what do you do when the £500 fridge breaks? You bin it. Making units that last long enough not to care is a reasonable approach. See also: new cars. Good luck getting spares for a Tesla or an MG for example.

 

In practice they're usually in production for a while and nitshit breakable parts (flap motors etc) are usually common between all vendors that if it were an issue there'd be some person sat at home with an eBay shop full of plastic gearwheels etc. Matey with a Rotex HPSU wound up buying some small plastic gear wheel for a control valve for 50p from such a vendor locally "they always break after about 5 years here's the widget type affair. Wouldn't concern me.

[Beelbeebub]

1 hour ago, markocosic said:

The risk is minor. Most leaks would be small and dissipate. Certainly minor vs the 2x 15 kg propane cylinders in "calor gas heaters" that you're permitted to keep indoors today.

 

If it were a problem you'd vent the installation to atmosphere (fridge lines in ducts; all joints within enclosures; vented to an outdoor space) but they're not even asking that in the proposed regs.

Agree!

 

1 hour ago, markocosic said:

Joints won't be pushfit with propane. They'll be flared and screwed. It's under decent pressure in a fridge system

Sorry, what I meant was "not brazed joints", flare nuts would be fine but if there was an even more foolproof way (Daikin has a clever one with a green indicator to show it's done up properly) it would be better. It needs to be plug and play 

 

 

As for spares, yes if the system was cheap enough then just replace (hardly very sustainable tho!). The pig is installation.  Swapping out a single head or outside unit is not too bad, but if you're replacing all the heads, the outside and then maybe the control wiring  it becomes a bigger job.

 

Be nice if it was a simple as a radiator swap.

[HughF]

I'm a member of the Polish 'heat pump open source monitoring' facebook group - lots of interesting stuff going on over there with various people DIY'ing heat pumps from old AC units, and/or gutting the indoor unit of a mini split to make it into a water heater.

 

I'm this close to getting another one of those ElectriQ r290 mini splits and running the refrigerant circuit through a coil of pipe stuffed into my immersion heater hole...