Calorex heat pump issues... A juicy read...

[back2space]

Hey guys...

A juicy conversation has been going on over at one of the other forums I participate in...

Its regarding a calorex heat pump that was already installed when the op moved into his new build house. The heat pump was specified as part of the planning regulations and all the other houses have gas central heating. The calorex seems to be designed for 7C outdoor temp and functions well at this temp, however below 3C and its duty really drops off very quickly. Must be one of the worst heat pumps that I have seen and its data sheets only confirm its output down to 0C (most systems are down to -15C these days)

The system wont heat below 5C and the op is having major issues and a fight on his hands with the builders who want to put more immersion heaters in that will come on to boost the system when it drops below 5C... putting his electricity usage up even further!

He could not get his house above 16C when it was at 0C outside that was with the system running night and day... hot water however was fine and sufficient. He has now just got his electricity bill which is as high as his neighbours who have a gas boiler and were toasty warm during the cold spell.. money down the drain I said you might as well be using electric heaters at least you would be warm.

Anyway i'm rambling on but the op is going to be taking legal action against the builders soon as they are not being very cooperative and the op is not happy with them fitting 2 separate heat pumps and all these immersion heaters so that it has the duty that is required...

It starts here http://forums.moneysavingexpert.com/...464827&page=18 post 697 is the technical report carried out by the builders, prob the best place to pick it up from.

Many people have replied and other people have also come on with their own problems in between but you will pick the jist of it up.

The op is bushyh -

What do you all think to this then? Any suggestions on how the op could take this forward.

I have suggested ripping the unit out and fitting something like a Daikin or Mitsi as these will work below 5C!

[charlie patt]

fixed speed fans fixed speed comp 20 dc ambient change simples

[thebigcheese]

sounds very like another job i heard about,
i bet theres hundreds of people in the same situation

[Brian_UK]

I think that he has had enough information information provided on that site.

It is time for him to call in the legal team methinks.

Get in a true independent to calculate the requirements and put that forward.

Design temps are tricky, what we think is right does not always tie up with what's written down the BS only designs on -1°C if I remember rightly.

The 0.6ac/h is only for building air tightness, ac rates between 1.5 and 2.5 are more the actual usage figures.

[charlie patt]

last year we fitted a what i call a plumming heat pump ie a heat pump that is made by one of the water boys ie worcester for the local council as a test for fuel efficientcy i did ask at the time if they wanted a mitsi or a daikin but what do i know,anyway we fitted this system it was not a invertor and not even fan speed control they fitted a elec meter and saw it spin relentless and then said it was to expensive to run one tip guys stick to a main brand we have now fitted a mitsi in the last three months the customer is happy and the elec meter is 52 percent less than last year

[nevgee]

My experience of Air Source heat pumps and their performance has been quite varied. I often find initially the operator has some ill perceived idea that the ASHP will perform in a simillar fashion to the old boiler. They expect virtual instant heat and have difficulty in grasping the reality that ASHP's do not produce heat as quickly as boilers. This then becomes a dissapointment and the foundation of future complaints and grumbles.

I also believe that the designers, Architects, consultants etc have a tendancy to hold too much faith in the "magic" of Heat Pump technology applied to even tighter heat loss calcs, usually quoting the SAP as being the ultimate guide for an acurate heat loss. Their aim to achieve super low energy figures to to gain merit in the portfolios. By utilising low U values and air change factors etc which seem very conservative in comparison to the older traditional methods of heat loss calcs, they can quote low heat loss figures. They apply low factors such as Air changes of 0.6 which is very low and probably not realistic during normal use of the qwelling as when people are coming and going thru external doors.

Then the ASHP is selcted generally with min safety factors and probably at operating ambients too high for todays design condtitions. -3 was normal, -5C is common but realistically , because we are looking at low energy, perhaps -15C should be considered.
However, there is the cost to be considered, and claims of higher cop's by the manufacturers, every one is clammering for a sale. SO, selection is kept tight, compromise then spoils the design and a just fit for duty is applied. Low energy = slow output = cool dwelling and cold occupier.

Then I have noticed that occupiers are not conservative in their management of the heating system, they don't keep doors and windows shut and so the heating system begins to struggle, and more so in extreme low temps. The occupier forgets that the heat source is a low energy low temperature. They expect to feel radiant heat from radiators, as with 80C flow temperature from traditional boiler. But they don't get this with ASHP, they can't have heating turned on just so, they need to learn to be patient and wait for it. They need to manage the heating differently, so the system has time to heat the building fabric and then once there it will act like a storage radiator, keeping a maintained background heat, which can then be lower than traditional settings. Under floor heating seems to satisfy occupiers better, perhaps they see it as a "new" style and are more patient. It is without doubt that ASHP's are better applied to Uf heating, but they do work well with rads if the system is managed correctly.

Then there are the installing Plumbers who admit their ignorance ... "don't know what these are " and proclaim ASHP's are mystical things beyond their understanding. (two connections flow and return?)

It's common for AShPS to be blaimed for all problems with the heating. ASHP's appear to be the scapegoat for all heating problems, from air locks to pump failures. When I discover badly installed piping, wrong wiring etc, the plumber, the sparky, all blaim the ASHP. Then the builder, developer can't explain away the poor performance, can't passify the owner because he is the middle man caught out by an eagerness to turn a profit and the slick moves of the Architect / Consultant, equally out for creditability by striving keeping the world green. Their only solution is to turn back to the old ways and offer, immersion heaters, Bivalent systems, surely if they'd got wise in the begining this problem wouldn't be with them now.

I know of properties where there are Calorex AW1200 units, some in pairs, have been working well, down to -18C. as claimed by the occupiers, who seem pleased with the performance. The attached Data sheet shows these units are capable of running at -15C

I know of sites where units (Daikin, Delonhgi) have been replaced with Calorex. I'm not saying iether or any are bad or better than each other, but the way these machines are perceived to be a dissapointment I think comes about through wrong expectations, bad selection and poor installation.

ASHP DATA SHEET.pdf

[Bigfreeze]

I agree. You can have the best heatpump in the world but if you don't have the knowledge on how to maximise its performance its no better than any other.
There are units out there that are just plainly designed wrong from manufacture also.
I never agree with matching rads and heat pumps. If you want rads stick to oil or gas. Heatpumps are just not compatible.
I also do not understand the obsession with ASHP's in the UK. People should really investigate, as far as possible, horizontal or vertical collectors before ever considering air source.

[Gary]

They are saying the water side dT is 6C, but they don't say what the flow rate is. I don't recall the exact formula, but I'm thinking if you know the dT and the flow rate you can figure out the exact heat output.

To take this a step further: As i understand it, the water flows through the ASHP condenser and then through an electric booster. If we know the output and the dT of the booster, we can figure out the flow rate. We can then use that flow rate and the dT of the ASHP condenser to figure out the ASHP output.

[MikeHolm]

500 x Qw x dT in imperial

500 x 10gpm x 10F = 50000btu

[back2space]

Over on the other forum it is full of complaints from people who have had bought a house with a heat pump specified by the property developer and it is undersized and not upto the job...

This link is about the NIBE Fighter 360 exhaust heat pump... Manufacturers need to ensure their dealers and installers are only selling to qualified people as its the manufacturers who are getting the bad name as people dont understand the sizing rules etc!

See link:

http://forums.moneysavingexpert.com/....php?t=2959648

[Gary]

500 x Qw x dT in imperial

500 x 10gpm x 10F = 50000btu

Thanks, Mike.

[mad fridgie]

I agree. You can have the best heatpump in the world but if you don't have the knowledge on how to maximise its performance its no better than any other.
There are units out there that are just plainly designed wrong from manufacture also.
I never agree with matching rads and heat pumps. If you want rads stick to oil or gas. Heatpumps are just not compatible.
I also do not understand the obsession with ASHP's in the UK. People should really investigate, as far as possible, horizontal or vertical collectors before ever considering air source.

May I ask what is the installed price (ball park please), of say a nominal 12Kw (single phase) vertical GSHP (many homes in the UK just would not have the garden for a horizontal system) price to point of application, "buffer tank for example"!

[MikeHolm]

In Toronto it would be about $30-35,000 US or CDN (same thing these days). 4 holes 200 ft deep. System would be doing forced air so this would include an air handler but no ductwork. For UFH, I would have to know more about the building.

Lots of people do horizontal here if they have the room and still they have return temps around 0C.

[mad fridgie]

In Toronto it would be about $30-35,000 US or CDN (same thing these days). 4 holes 200 ft deep. System would be doing forced air so this would include an air handler but no ductwork. For UFH, I would have to know more about the building.

Lots of people do horizontal here if they have the room and still they have return temps around 0C.

Thanks Mike, then what would be the price to the same stage for an ASHP

[mad fridgie]

A Toshiba (genuine japanese) 18kw air to air ducted system (without the ducting) installed would be around the US7.5K in NZ, (just but one in for my mate, so he got quite a lot cheaper) not my core business.

[Gary]

They are saying the water side dT is 6C, but they don't say what the flow rate is. I don't recall the exact formula, but I'm thinking if you know the dT and the flow rate you can figure out the exact heat output.

To take this a step further: As i understand it, the water flows through the ASHP condenser and then through an electric booster. If we know the output and the dT of the booster, we can figure out the flow rate. We can then use that flow rate and the dT of the ASHP condenser to figure out the ASHP output.

500 x Qw x dT in imperial

500 x 10gpm x 10F = 50000btu

Hmmm... If we know the total heat output and the indoor and outdoor temps, then on a warmer day when the system is cycling we can factor in the percentage of run time and accurately figure out the heat needed for that outdoor condition... and if we do the same for two or more outdoor conditions, we can then plot the heat needed for any outdoor condition. Does this make sense?

[nevgee]

Hmmm... If we know the total heat output and the indoor and outdoor temps, then on a warmer day when the system is cycling we can factor in the percentage of run time and accurately figure out the heat needed for that outdoor condition... and if we do the same for two or more outdoor conditions, we can then plot the heat needed for any outdoor condition. Does this make sense?

I would believe so, we used to do heat balance graphs, system performance across differing ambients against building loss. Then a balance can be obtained for the range which would indicate a negative performance point, at which supplimentary heating would be required.

[nevgee]

They are saying the water side dT is 6C, but they don't say what the flow rate is. I don't recall the exact formula, but I'm thinking if you know the dT and the flow rate you can figure out the exact heat output.

To take this a step further: As i understand it, the water flows through the ASHP condenser and then through an electric booster. If we know the output and the dT of the booster, we can figure out the flow rate. We can then use that flow rate and the dT of the ASHP condenser to figure out the ASHP output.

Qt = m.cp.dt

kW= kg/s x 4.187 x K

[Bigfreeze]

May I ask what is the installed price (ball park please), of say a nominal 12Kw (single phase) vertical GSHP (many homes in the UK just would not have the garden for a horizontal system) price to point of application, "buffer tank for example"!

Weather compensated brine to water unit, straight to ufh would be in the region of 11-13K (manufacturer dependant) installed including vat but excluding drilling

[nevgee]

May I ask what is the installed price (ball park please), of say a nominal 12Kw (single phase) vertical GSHP (many homes in the UK just would not have the garden for a horizontal system) price to point of application, "buffer tank for example"!

I understand uninstalled delivered prices;
Calorex ASHP 12kW List £6283.00 GBP
Calorex GSHP 12kW £5648.00 GBP

[Bigfreeze]

I understand uninstalled delivered prices;
Calorex ASHP 12kW List £6283.00 GBP
Calorex GSHP 12kW £5648.00 GBP

You can double that for installed when you included divertor valves, pumps, glycol, exp vessels, piping, labour, vat, mark up etc etc.

[Gary]

I would believe so, we used to do heat balance graphs, system performance across differing ambients against building loss. Then a balance can be obtained for the range which would indicate a negative performance point, at which supplimentary heating would be required.

Qt = m.cp.dt

kW= kg/s x 4.187 x K

So... given an existing structure with a system that works well enough to do the job in mild weather, we should be able to tell if the system is sized properly and/or working to manufacturer's specs. If we are going to replace that system, we would know exactly what size the new system would need to be to handle a given indoor/outdoor temperature difference. We can take the guesswork out of heat load calculations.

[MikeHolm]

Wow, I guess I have not been on this thread for a bit. ASHP and I have one going in right now, 150m2 floor heat, 1/3 in 100mm slab, 2/3 in 40mm gypsum cement overpour on plywood subfloor, HP is a packaged unit being split to have the comp indoors, york product (under one of its many names), 15kw. One 300L buffertank for heat, one smaller for cooling through an air handler (separate BPHE for heat and cool), Solar thermal preheat for DHW (I am not going to integrate it into the space heating this time.
Cost about $32k for everything

[MikeHolm]

I am definitely not overpricing this one. Correction on the price, $36k

[Bigfreeze]

I am definitely not overpricing this one. Correction on the price, $36k

Mike, the prices quoted above would be heat pump only, no buffer, no dhw tank and not including ufh.

[MikeHolm]

If it did include everything, I would buy it from you and make a tonne of money selling it at my pricing.

I will have to look at my cost for the GSHP but the ASHP base unit I am buying lists for around $7500. What I am buying this time is just the HP (coil, comp, TXV, reversing valve etc.) with no components internal to the house.

I don't know what kind of supplier discounts you get.

[Bigfreeze]

If it did include everything, I would buy it from you and make a tonne of money selling it at my pricing.

I will have to look at my cost for the GSHP but the ASHP base unit I am buying lists for around $7500. What I am buying this time is just the HP (coil, comp, TXV, reversing valve etc.) with no components internal to the house.

I don't know what kind of supplier discounts you get.

Every supplier has their own way of applying discounts. Some have higher lists with 50% discount, some have lower at 30% and others depend on the volume you buy. Its all over the place really

[MikeHolm]

Given the above system in a heavy mass, you must be moving the water quite quickly through 80m of tubing (15-16mm?) to get a dT of 5C. What are the design flow rates and am I right about the tubing size?

The typical infloor systems here use 1/2" ID tubing in the floor.

[MikeHolm]

We tend to design our floor tubing for a 20F dT with boiler systems and I suppose that with a buffer tank this would be fine when using a HP, but not if it were, as above, with a "direct to floor system".

Our tubing is 1/2" ID and 250' in length generally. What diameter tubing do you normally use to get your 5C dT and typically at what flow rate?

[Bigfreeze]

We tend to design our floor tubing for a 20F dT with boiler systems and I suppose that with a buffer tank this would be fine when using a HP, but not if it were, as above, with a "direct to floor system".

Our tubing is 1/2" ID and 250' in length generally. What diameter tubing do you normally use to get your 5C dT and typically at what flow rate?

The tubing is 15.5mm with a 1.5mm wall. The flow rate we require across the condenser of our 12kw unit is 2000 litres per hour so that means a flow rate of 33.3 litres per minute in order to give you your 5k DT. We usually go for a slightly higher flow rate as we usually get between 13 - 14kw return from that machine due to collector design and ufh design.

[MikeHolm]

Thanks BF. Is it common to have a VFD on that pump based on actual output vs outdoor temp (or pressure or another indicator) ? The comp is working just as hard regardless of the OD temp.

[MikeHolm]

The SDR9 tubing we use is within 5% diameter and wall of the metric. I got pissed off at REHAU for switching to imperial as they went from a 2mm wall to a 1.5mm+- and I thought they were getting cheap but the heat transfer was a bit better and the price went down. All this to compete with Wirsbo who had been making it here for a couple of years and used the imperial measure.

On a related note, do you have any comments on oxy migration through the tubing. When we used Pex/al/pex for floor heating, we would see more oxygen induced corrosion on pump bodies than with the REHAU tubing. My belief is that when the Pex/al/pex makes a bend, the aluminum breaks at the bend and the barrier is compromised.

[MikeHolm]

I suspect that there is a lot more engineering in the Calorex HP or NIBE HP than in our basic units made by the bigger companies who see residential HPs as a sidebar to AC systems. Maybe in the 25% greater cost there is worth it??? At least the controls seem to have more options for the installer or end user.

[Bigfreeze]

Thanks BF. Is it common to have a VFD on that pump based on actual output vs outdoor temp (or pressure or another indicator) ? The comp is working just as hard regardless of the OD temp.

No we only use variable speed pumps on our fully modulating units. They speed drive the compressor in relation to the weather compensation.
On direct on units there is no benefit of a variable speed pump. Up to 12kw we would generally use a 25mm pump with a 6m head, its such a small pump the running costs involved are miniscule

[Bigfreeze]

I suspect that there is a lot more engineering in the Calorex HP or NIBE HP than in our basic units made by the bigger companies who see residential HPs as a sidebar to AC systems. Maybe in the 25% greater cost there is worth it??? At least the controls seem to have more options for the installer or end user.

The units from HP manufacturers tend to have a greater respect for the protocols one should follow in order to have an efficient system and their controls reflect that. Quite a few cop out at the critical last 10% that makes a system really efficient (like excluding immersions) in order to keep costs down.
Theres only about 5 companies that go the whole hog and try to do everything well.
The AC units are all about cost and trading on the heatpump name. They try to be all things to all men and thats something no machine can be.

[MikeHolm]

Yes, I'll agree with you there. I fully expect that I will have to create a custom control unit or find one that is designed well for heat pumps. To that end i did find the Seimens RWD44 and 45 series controllers. Anyone have any knowledge of these units? Are they a reasonable controller? Any other one to recommend?

Where does Danfoss and Viessmann rate on the list of HP all stars?

[Bigfreeze]

Yes, I'll agree with you there. I fully expect that I will have to create a custom control unit or find one that is designed well for heat pumps. To that end i did find the Seimens RWD44 and 45 series controllers. Anyone have any knowledge of these units? Are they a reasonable controller? Any other one to recommend?

Where does Danfoss and Viessmann rate on the list of HP all stars?

If you're going to the bother of designing a Heat pump then get a PCB designed to suit your system. I've never seen a generic controller than will do the job you want without compromise.

I'd put Veissman at about 9th and Danfoss at 11th in my list of top heat pumps on the market at the moment.

[MikeHolm]

That makes me really curious as to who are the top 5

[MikeHolm]

As I mentioned somewhere else in the forum, although I have the resources to design the PCB and program it, in N.A. the process to get it approved by CSA or UL is way too onerous.
In the solar thermal business there are 30 or 40 good companies making controllers in Europe (some of them with sales of only 300-400 units) and the CE process for them is straight forward and at a reasonable cost.

Not so in N.A. We cannot put anything on the market without a full 3rd party testing and you are looking at up to a year (or more) and 10s of thousands of $$$$$.

If you google solar controllers from N.A. you might find 1 or 2 but most are from Europe. The process stifles creativity. So, for that reason, I kind of need to use a pre-approved controller especially as the systems I work are mostly residential and building inspectors want to see approvals.

[mad fridgie]

Could not use a small PLC, for example Allan Bradley, Omron, they do produce some quite cheap ones nowadays, then write software (you are able to protect within the unit its self) this would save the requirement to get ratings. Or you could approach from a different angle, think of the heat pump as stand alone, with its own dedicated controller, primarily covering defrost and protection (plenty of the instruments available, carel, invensys etc. Have a digital input to start the system, this will come from a seperate controller, which controls the water temp in your buffer, many have temp offsets/compensation facilities

[MikeHolm]

Tis true, a small PLC would do. We do have some good DDC controls here KMC or Reliable that I could use but although i have worked on systems with them, I have never programmed them so its another language to learn.

Still curious who the top 5 would be or am I not supposed to ask?

[russgibb]

I agree. You can have the best heatpump in the world but if you don't have the knowledge on how to maximise its performance its no better than any other.
There are units out there that are just plainly designed wrong from manufacture also.
I never agree with matching rads and heat pumps. If you want rads stick to oil or gas. Heatpumps are just not compatible.
I also do not understand the obsession with ASHP's in the UK. People should really investigate, as far as possible, horizontal or vertical collectors before ever considering air source.

Hi Bigfreeze.
I'm sorry, but I have to disagree with you. Heat pumps work well with radiators as long as the rads are sized for low temperature flow. The key with any successful heat pump installation (of which I have had many, and "learning moments" with a couple) is to ensure you understand exactly what's happening through the whole operational envelope. I.e. what the flow temps are when it's an external ambient of -15C through to +16C. I have had a heat pump heating my house perfectly for 4 years and I didn't even bother replacing the scabby un-finned single rads, although I intend to one day!
A heat pump will fully satisfy your customer if the flow temperature is as low as possible to heat the house adequately, right down to exceptionally cold weather conditions, like we've had in Scotland during the past two winters.
Know the theory and the technology you are specifying and you won't go wrong.
Regards, Russell

[eiffel]

is it a true? o my god! i have ordered 1 piece heat pump from the calorex.

[chillerman2006]

Off topic - needed removing