Mitsubishi Ecodans ASHP issues...

[Bigfreeze]

This is all well & good in theory, but what about in practice?


How many domestic homes will have space for all this paraphanalia?

This is where the low loss header will rule as it needs zero space in comparisson to buffer tanks etc.

You don't get many homes with room for a dedicated ASHP Plant room do you?

Its only the width of a tank, 600 -700mm, and its the diference between a properly designed hydraulic circuit or a half way house designed for an oil boiler. Your choice

[mad fridgie]

This is all well & good in theory, but what about in practice?


How many domestic homes will have space for all this paraphanalia?

This is where the low loss header will rule as it needs zero space in comparisson to buffer tanks etc.

You don't get many homes with room for a dedicated ASHP Plant room do you?

In 2 storey houses we normally install the manifolds and a tall skinny low loss header under the stairs.
The object of the buffer and the tall vertical low loss header is to keep maximum seperation between the hot supply and cold return, whilst still having the ability to ensure correct flows.
In the horizontal one in the pic, It would seem that mixing of the hot and cold streams would occur, derating both the heat pump (higher entering water temp) and the heating appliance (lower entering water temp)

[brunstar]

The main problem with heat pumps is the installation, as you can see in the mitsi pictures that the units should be protected from the snow and a snow cover should be installed over the units to stop the snow from accumulating on the unit.

It is evident not just in heat pumps but also in general day to day life that people in the UK are not ready for the snow.

Snow should be cleared from areas.
The other thing is that is if you look behind the unit there is a lot of snow also.

Looking at the Daikin picture, wozza is right the unit is not off the ground, if it is sub zero then how can any condensate get away from the unit.

In relation to the running costs of the Ecodan units i do not think that your running costs are high at all for a 24 hour period.
I am sure that you oil bill or gas bill for a system that has 31 radiators would not be cheap either.

I do feel that a shelter from the snow will solve the majority of your problems.
If you want to reduce the running costs over a 24 hour period, if you are turning them off then try to turn one of them off and reduce the flow temperature so they are ticking ove which will reduce the running costs.
If you do not run out of hot water then try dropping this temperature by a few degrees also this will make a big difference.

[Gary]

I'm betting solving the defrost problem will do wonders for the running costs.

[brunstar]

One thing that we need to check is that are you taking the KW hours of the heat pump only or is this all of the power consumption for the property.
A lot of people have increase power bills with heat pumps but they do forget about the oil or gas bill that they no longer need to pay.
Is this the heat pump KW hours only or the total as lights, power and cookers also add to running costs which we forget about.

[nevgee]

I'm in agreement with Gary here. It's so obvious there is a problem with the defrost cycle. You can postulate all day long about fin spacing etc but this is no different to a cold room or any other application. frost build up over all, is down to the fact that there is insufficient time or heat distribution to the whole coil area to remove the frost. These units are outdoors so subject to every variation of ambient change, unlike a cold store.

The next question is why does the frost build up to such a level? Insufficient time, insufficient defrost heat, insufficient defrost periods?

[mad fridgie]

If you look on picture 1 and 5 you can clearly see thermal bridging between the coil and the case. The coil could and it look likes that is does clear during a defrost, but does not clear the ice build up on the casing. What causes the bridging, incorrect defost, or snow. If snow how do over come the problem, with in the present control scenerio.
Either ensure snow does not enter, or ?????? with the electronics.

[TiredGeek]

What causes the bridging, incorrect defrost, or snow. If snow how do over come the problem, with in the present control scenario.
Either ensure snow does not enter, or ?????? with the electronics.

I can clear this up right away
Pictures 4 & 6 show the failure from last year in early November when ambient was only -3'c and there had been no snow at all.
If you look at 4 you can see one unit is fully covered with ice, the other has none.
That is because one had burnt out a fan and blown an internal fuse, shut down, and defrosted in +'c ambients. The other had continued running with damaged fan blades and maintained it's ice by continually trying to heat the house from it. Maybe this year snow blew onto the forming ice sheet and stuck.

This IS a defrost issue. I have witnessed it do it. The indoor control says "defrost", the outdoor starts the cycle, makes a "humph" noise and then shuts down and does nothing (throws code D6 for those in the know).
After a few mins the indoor says "heating eco" and the outdoor starts up and tries to produce heat. This obviously drops the temp of the fins and causes the frost to thicken.
It is now in a cycle from which it cannot escape - no heat output from the unit so nothing for it to draw on to do a defrost = failed defrost, then it tries heating again, no output from unit etc etc.....

I am in touch with someone I will call an EcoDan GOD as he seems to know the specific unit better than Mitsubishi's own tech. A low loss header is going to be tried asap, but unfortunately I won't be able to get it fitted before spring so the system will not be "proven" until they've gone through next winter....
He thinks it's a combination of low water flow and low temp returning water having insufficient energy for the EcoDan to draw on for a defrost (I think I have that right ) A low loss header may sort it, it certainly won't hurt.

[brunstar]

Very intresting this thread!

It does sound like your pipework setup is causing control problems possibly?

My own setup albeit using an Altherma uses a low loss header.

I have 28mm flow & return from the indoor unit going to a Vaillant low loss header.

The 2 outputs in 28mm drop down 600mm or so and then T off to 3 22mm heating loops round the house (3 storey house)

Each loop has it's own Grundfoss Alpha2 15-60 pump serving each floor via a programmable room stat and 2 port valves.

The pump from the Altherma does nothing more than pump from the indoor unit to the header and back.

Below pix may explain better!

Sinewave, nice install, the only thing that i can see is that your flexies are twisted which will put undue stress on the crimped sections of the pipe.. The red line should run straight along the pipe.

Nice install.

[sinewave]

Funny you should notice that Brun!
That Flexi has leaked from Day 1 and initialy I thought it was the washer which has been replaced twice, but it turns out it's the crimp leaking.
It's twisted due to too much tightening before the faulty crimp was finaly deduced!

The Red line was straight initialy!

[brunstar]

some methods use both time initiated before the last defrost, outdoor ambient temperature and outdoor coil temperature aswell as head pressure termination.
Another important point is units as per the air to water can also terminate if the plate heat exchanger temperature goes below zero to protect the plate heat exchanger in the event of low flow through the plate heat exchanger, in my experience they are usually down on water flow rates through the plate heat exchanger as the pipework installed on the water side usually offers too much static pressure if not designed correctly IE: everything in 22mm and 15mm copper.

By increasing the fin spacings this would make the situation worse on an air source heat pump as it would reduce the coil surface area so during a defrost the heat would not be distributed as well and same goes for absorbing heat to evaporate the liquid out of the coil in normal heating operation.
Freezer rooms are ok with wider fin spaces as those rooms usually have a lower humidity and a much more controlled environment.

[TiredGeek]

Well, I've had a header design priced up and it turns out it's about a third of the price of making it myself with 42mm pipe and T pieces (£135+ versus nearly £400 in parts)
So that's going to be ordered.
http://www.vaheating.co.uk/headers.html

The only problem I have now is that it's not going to be fitted until this winter is over so there is no way of knowing if it helps with the problem until next year.....

I have found something else that may be of interest to others though.
Amazon do a reptile tank thermometer for £5 that has a long lead with a probe on the end, reads every couple of seconds, is accurate to 1'c and does -10'c to +110'c.
I'm attaching one to every damn pipe I have and at least then I know what all my water temps are
http://www.amazon.co.uk/LCD-Digital-.../dp/B001U49TUM

[MikeHolm]

Well, I've had a header design priced up and it turns out it's about a third of the price of making it myself with 42mm pipe and T pieces (£135+ versus nearly £400 in parts)

Google "Flowdrill". I have one of these and with a powerful enough drill you can extrude a tee socket into a pipe. I make my LL headers with it.

[TiredGeek]

The header and some swept bends I had them do me arrived today.

They've done a lovely job
The header is perfect, brazed joints and it's been polished up to look really nice, the bends are also very nicely done and just what I needed to keep the water flow speedy. Bargain prices (to my mind) and the box they came in could withstand even ParcelFarce as the thing is a custom built wooden affair, weighs a bloody ton!

I'm in no way affiliated with the company, but I believe that if someone does a good job then it should be noted, I'd be the first to complain if it was done badly

[fixmyheatpump]

some methods use both time initiated before the last defrost, outdoor ambient temperature and outdoor coil temperature aswell as head pressure termination.
Another important point is units as per the air to water can also terminate if the plate heat exchanger temperature goes below zero to protect the plate heat exchanger in the event of low flow through the plate heat exchanger, in my experience they are usually down on water flow rates through the plate heat exchanger as the pipework installed on the water side usually offers too much static pressure if not designed correctly IE: everything in 22mm and 15mm copper.

By increasing the fin spacings this would make the situation worse on an air source heat pump as it would reduce the coil surface area so during a defrost the heat would not be distributed as well and same goes for absorbing heat to evaporate the liquid out of the coil in normal heating operation.
Freezer rooms are ok with wider fin spaces as those rooms usually have a lower humidity and a much more controlled environment.

If this was facebook I would "like" this!

[TiredGeek]

Ok, another question. This time about weather compensation.
From what I understand the EcoDan works this fairly crudely, the controler has a "ramp" of temperatures to output the water at relative to the outdoor temp.
So if it's set to do 25'c @ 17'c ambient to 40'c @ -5'c ambient, it measure the temp of the air passing through it, say 5'c, and compares that to it's internal "temperature ramp" and sets the output accordingly, say 30'c.

Am I correct in this thinking or is it a more clever system that compares return temperature of the water and other factors as well?

One other interesting thing I found yesterday.
The company I used supplied me with an instalation manual which we worked from. I happened upon an updated version of this manual, from the same company, whilst poking around on Google. Since they sent me mine which was 25 pages long, it has been somewhat revised and now runs to 68 pages!
I wonder if there's something in there they've learnt since my install, I'll have to read through it and find out.......

[Jon Glanfield]

Hi tired Geek, I just wondered whether you had kept pace with another thread on here, reference flow temperatures on an Altherma.

It might be worth a look. We used a header also constructed by VA Heating on that job, but it is exhibiting the symptoms described by Big Freeze earlier in your thread, namely mixing and artificially affecting the return temp.

There are other issues on that particular job, but it might be an idea to give the buffer idea some research. We have asked Mitsubishi for their views on using a buffer with the Ecodan and will let you know their response if you like.

Cheers

Jon

[MikeHolm]

About outdoor reset controllers: most units base the reset on a value of .5 to 2.5C increase in temp per deg drop outdoor (depending on heating type ie: UFH, rads, scorched air etc) as well a parallel curve to allow the whole thing to shift up or down the scale. Is this the case with the HP programmers?

[Bigfreeze]

Not sure what you mean by outdoor reset controllers Mike. Are you referring to weather compensation?

[MikeHolm]

Yes, a lot of the manufacturers call it outdoor reset as it resets the operating conditions but there are a number of others including weather compensation.

[mad fridgie]

I have a question, temp compensation, i understand the principle and makes great sense, match you heat output with your heat requirement, I also understand that you can adjust your angle of deviation to suit the particular property, but what i do not understand is why on such a system would still have flow issues. Simply energy can be experessed flow * temp difference, so if you are slowing your flow you must have to raise the temp for a give amount of energy, which is counter productive for the efficiency of the heat pump.
Do you guys use air thermostats ( I do not)
Maybe i am not expalining my self well?
Your house losses energy on a second by second basis, in an ideal world we should be able to match the losses second by second. An inverter would seem the way to go (totally variable output within its limits) a fixed speed machine will stop and start, so when running has to produce more energy to compensate for when it was producing none. But what actually heats your home, it is the floor, so are you better to keep the whole floor at a lower temperature with high flow rates or just a small proportion of the floor at a warmer tempertaure at lower flow rates. In my opinion high flow rates and low temps, best for system efficiency, so why do you reduce flow, if you reduce the flow temperature? and then up with an poorly balanced hydronic system, hence the buffer tank masks, poor design. (understand the need for thermal buffer for defrost, different issue)

[MikeHolm]

OK, the first issue is time lag... especially in a floor. There is no need to set and reset every second, every minute will do. Estimating the needs of the house is relatively easy with a well defined program including hysteresis. The problem used to be with single speed pumps (solved) and single stage boilers (solved...to a degree with condensing and modulation, negative pressure gas valves and all that) and with inverter heat pumps (solved to a lesser degree due to the tighter operating tolerances of HPs in general over boilers).

What happens when a really cold wind comes up sucks the heat out of a house within 10 min? No floor heat will compensate easily for that but it certainly does help. I did a loading dock and warehouse for a national supplier and as soon as the door opened, it froze in the building but as soon as the door closed 30 sec and it was warm, but they had 30cm of concrete to hold the heat. That is the same idea as the buffer tank in a way.

As much as I would like to reduce flow rates in the floor to save on pumping power (and tubing degradation over time) I see your point about higher flow rates. Buffer for defrost, low floor temps to keep COP high and a high enough flow rate to ensure that we don't get a 12C delta T over the floor. The slower you go the more liquid temp is lost over the circuit length.

That said, it is difficult for any system to accurately predict the weather future. This is great fun, far more interesting than boiler work.

[Bigfreeze]

It depends on the company. Some you can vary the curve yourself, others are preset at you pick the curve that suits your need best. In the ones you can vary you'll probably have a set up something like this
Outdoor temp Return temp
18 22
0 28
-15 33

which you would adjust depending on insulation levels

[Bigfreeze]

They only have flow issues where stats are involved and when you run stats you're not running true weather compensation so if you have flow issues its down to poor design

[Bigfreeze]

OK, the first issue is time lag... especially in a floor. There is no need to set and reset every second, every minute will do. Estimating the needs of the house is relatively easy with a well defined program including hysteresis. The problem used to be with single speed pumps (solved) and single stage boilers (solved...to a degree with condensing and modulation, negative pressure gas valves and all that) and with inverter heat pumps (solved to a lesser degree due to the tighter operating tolerances of HPs in general over boilers).

What happens when a really cold wind comes up sucks the heat out of a house within 10 min? No floor heat will compensate easily for that but it certainly does help. I did a loading dock and warehouse for a national supplier and as soon as the door opened, it froze in the building but as soon as the door closed 30 sec and it was warm, but they had 30cm of concrete to hold the heat. That is the same idea as the buffer tank in a way.

As much as I would like to reduce flow rates in the floor to save on pumping power (and tubing degradation over time) I see your point about higher flow rates. Buffer for defrost, low floor temps to keep COP high and a high enough flow rate to ensure that we don't get a 12C delta T over the floor. The slower you go the more liquid temp is lost over the circuit length.

That said, it is difficult for any system to accurately predict the weather future. This is great fun, far more interesting than boiler work.

Weather comp will usually take an average temp over the course of an hour and adapt the required return temp to that level. Even if the weather changed dramaticly its highly unlikely that the house temp would change much in that time so the HP usually has plenty of time to keep pace.

Ideally you'd try to have a DT of 5C across your floor which would give you 5C across your condenser, which would be optimum for HP performance

[mad fridgie]

Have you guys ever used a black thermostat?

[mad fridgie]

Temp compensation is not used a lot in NZ, many would like to say it is because of our unique conditions, but it comes down to how the houses are built and finished/furnished. Temp lag is normally the biggest issue.
I have seen many a good system fail, because the interior designer decides as an after thought that a 2 inch **** pile carpet through out the house would make the house look good.

[Bigfreeze]

Black thermostat?

[Bigfreeze]

We have plenty of those here too. More concerned about the final finish than the actual structure of the house and the insulation, but things are getting better. Carpets are a killer for ufh systems as the underlay used is rarely correct

[MikeHolm]

Sorry Mad, what is a black thermostat?

Not just carpets but really thick hardwood floors cause trouble.
We've been having some 15-18C temp swings lately so the same issues can exist here as in NZ. It, unfortunately, makes the case for fast acting systems like scorched air. I will never give up on the floor heating...the dogs love it too much.

[mad fridgie]

Black thermostat!
Story line first. In NZ the buzz word at the moment is "Passive", which most just equate to heaps of windows (but that is another issue) north facing (we are in southern hemisphere), but many simply do not understand about thermal mass. The sun is very strong in NZ even in winter, so even when cold outside dry bulb temp in the sun you do feel warm and houses do warm up through lots of windows (they cool down just as quick because of the poor quality of the windows installed) How do they make the most of the energy, a simple black strip in frount of the windows (absorbs heat) but nothing like the total that could be absorbed. What i have done in the past is have a manual over ride on the water pump (on) while the heat pump is off. The water pipes pass through the dark strip picking up energy and transfers the energy evenly through the house's concrete floor. How would you control this automatically. "A black thermostat" which I believe measures infra-red radiation, basically measuring the strength of the sun, not the temperature. Could this be incorparated into your temp compensation systems

[sumsor]

Hi Mad,
I'm working on two houses in QT at the moment.
We have a proper BMS setup to control UFH, Gas Boilers, HWHP, Radiators and a VRV system.
The system alows for weather compensation depending on o/s temperature and infrared radiation. The system controls the water temperature for UFH and Radiators and is also linked to the VRV system to offset the room sensor readings on days with lots of sunshine and low o/s temperature.
Haven't seen this in a domestic install yet though.

[mad fridgie]

Hi Sumsor,
A couple of houses in QT, nice, at least you should a reasonable budget to complete a decent job. Not like in ChCh, always on the cheap.
I never got to use the infrared control (pet client passed on), so never took it any futher. But in my opinion must be a benefit in a total control system
Do you have any info on the radiation sensor/ black stat you could post on RE, I am sure many would be interested

[sumsor]

Hi Mad,

all the controls gear is Siemens.
I'll try and get some more information, it would be intersting how the control is integrated into the system(values, setpoints, etc.) as well. I'll talk to the programmer when I get a chance.
In this special case it should be a great benefit as the whole housefront is glass.
http://www.sharearchitecture.co.nz/j...own-p-191.html

[MikeHolm]

OK, if by black stat we could use a radiation sensor or a pyranometer, we have been using them for years for testing light levels in the solar world. Gives you a w/m2 reading. What you do with that info is up to you. The ones we use look like a glass ball mounted on the roof. Your situation is different as ours has to have super high accuracy and also measures the suns angles etc.

I work on a lot of passive solar houses, comes with the territory, and i design the floor heating to take the heat to the colder areas of the house and I set the pump to circulate but so far only on a timer in parallel with the boiler or whatever.

I think we could devise a low cost sensor to do as you suggest, I'll send it to the design department for consideration (that would be the other side of the brain, the unused part)

[hjcmb]

Hi everybody, am new to the site, but wanted to join to tell you of an ASHP that i saw today that, i believe, is a game changer. Why? - because:

at A-19 it has a COP of 3.27 on a flow temp of 62c
at A0 it has a COP of 4.7 on a flow temp of 80c
at A+15 it has a COP of 6.83 on a flow temp of 81c

All models, there is a cmprehensive range from 4.5kw all the way up to 30kw off shelf, but will make bigger to order, have a db reading of 40 or below

All above figures confirmed as authentic by BSRIA

It uses a Sanyo compressor, Danfoss parts, but is not complex. I saw, and felt the 10kw and the 15kw in action, and they are phenomenal.

Now the real USP. They are totally retro fit friendly onto an existing radiator system, do not require or use an accumulator, just an exiting hot water tank, do not require back up, and get this, the 4.5kw is GBP3,007 installed, the 10kw is GBP3,815 installed, and the 30kw is GBP12,908 installed.

On those COP figures the ammortization is sub 3 years, even without the RHI.

To me a complete no-brainer.

[mad fridgie]

Hi everybody, am new to the site, but wanted to join to tell you of an ASHP that i saw today that, i believe, is a game changer. Why? - because:

at A-19 it has a COP of 3.27 on a flow temp of 62c
at A0 it has a COP of 4.7 on a flow temp of 80c
at A+15 it has a COP of 6.83 on a flow temp of 81c

All models, there is a cmprehensive range from 4.5kw all the way up to 30kw off shelf, but will make bigger to order, have a db reading of 40 or below

All above figures confirmed as authentic by BSRIA

It uses a Sanyo compressor, Danfoss parts, but is not complex. I saw, and felt the 10kw and the 15kw in action, and they are phenomenal.

Now the real USP. They are totally retro fit friendly onto an existing radiator system, do not require or use an accumulator, just an exiting hot water tank, do not require back up, and get this, the 4.5kw is GBP3,007 installed, the 10kw is GBP3,815 installed, and the 30kw is GBP12,908 installed.

On those COP figures the ammortization is sub 3 years, even without the RHI.

To me a complete no-brainer.

Nice set of numbers, what brand is it, and do you have a website. Must be a new technology

[hjcmb]

Hi Mad Fridgie - web site is http://ethp-ltd.com/aboutecotec.html but that only shows previous generation, (the one i saw today). The new generation is on its way to UK as we speak. They are updating the website also, as all the tech notes apply only to the previous generation. The owners have only just taken over the company from previous management - but definately know their stuff.

[Bigfreeze]

:

at A-19 it has a COP of 3.27 on a flow temp of 62c
at A0 it has a COP of 4.7 on a flow temp of 80c
at A+15 it has a COP of 6.83 on a flow temp of 81c
.

Can you explain how this is possible seen as it improves on anything currently on the market by about 50%. And thats over the top machines out there which would be 3 times the price. Seems a little too good to be true, if you don't mind me saying. Any affiliation to the company btw?

[Bigfreeze]

just fit dimplex

problem solved!

Or problem created, depending on how you look at it

[hjcmb]

I agree - I can't explain, but I've seen it in operation. All I can say is that they have gone back to drawing board and started from the beginning again - nothing was taken for granted. I was about to sign to install the Sanyo CO2 ECO, which had the best performance on the market, until I saw this in operation. On the 15kw machine, the flow pipe was too hot to touch in less than a minute. The other incredible thing - they were rigged up in a wharehouse, and running they were barely louder than a deep freeze. No I am not connected to the company at all - but I can tell you I wish I was. I shall be installing these - they sell themslves.

[mad fridgie]

at A-19 it has a COP of 3.27 on a flow temp of 62c

Done some calcs on this.
Ambient -19C, with a massive evap giving all benefit of doubt suction SST -21C
2 stage compression and 99% isentropic efficiency (for each stage)
Using every last ounce of discharge super heat and no heat losses from the system and excellent liquid sub cooling SCT 52C.
heat out put 9.8Kw input 2.7Kw cop 3.63, but then we need to include the fans, pump and defrost.
I do not think so, using the best of off the shelf components. Maybe they have invented some new, that being the case then is a world beater no just in heat pumps but all refrigeration.
Looked at the site, equipment looks good, COPs of 3.6 at ambinet of 0C and 45C water more realistic, can not wait to see the innovation

[Bigfreeze]

What the hell does the flow pipe being hot in less than a minute prove. I can get a flow pipe up to 80C in less than 30 secs if I starve it of water. Won't be efficient but it will be hot. Best of luck with the sales, I'll wait for some deeper info before I follow suit

[Bigfreeze]

at A-19 it has a COP of 3.27 on a flow temp of 62c

Done some calcs on this.
Ambient -19C, with a massive evap giving all benefit of doubt suction SST -21C
2 stage compression and 99% isentropic efficiency (for each stage)
Using every last ounce of discharge super heat and no heat losses from the system and excellent liquid sub cooling SCT 52C.
heat out put 9.8Kw input 2.7Kw cop 3.63, but then we need to include the fans, pump and defrost.
I do not think so, using the best of off the shelf components. Maybe they have invented some new, that being the case then is a world beater no just in heat pumps but all refrigeration.
Looked at the site, equipment looks good, COPs of 3.6 at ambinet of 0C and 45C water more realistic, can not wait to see the innovation

Theres two monkeys on a bike inside the casing driving the compressor and keeping the electrical consumption down. Only time the power kicks in is when they go on tea break

[mad fridgie]

Theres two monkeys on a bike inside the casing driving the compressor and keeping the electrical consumption down. Only time the power kicks in is when they go on tea break

Shush, keep your secrets to your self, or do you have a world wide patent on this already (or only in Ireland)
How many Kws do you get from a banana or do find peanuts are better value for money

[Bigfreeze]

One step ahead MF, patented, with first shipment of monkeys in transit. Our tests have shown that bananas and mild electrical shock gets the best bang for your buck, especially on the defrost cycle

[MikeHolm]

Bananas are on their way out, too squishy. You need a high energy compact source.....ummmmm...I've got it Uranium.....or darn, killed the monkey.

[Bigfreeze]

They're a bugger for clogging up the condenser alright

[MikeHolm]

As Gary would say "airflow, airflow, airflow". How does a banana change the PH, you will have to use titanium stainless condenser?

[Bigfreeze]

Mike, you're just ruining this for me now. I thought I was on a winner with this one. One of them tore a hamstring this morning and I didn't have enough hot water for my shower