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Re: Mitsubishi Ecodans ASHP issues...
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)
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
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.
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
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Re: Mitsubishi Ecodans ASHP issues...
Have you guys ever used a black thermostat?
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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)
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
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.
Nice set of numbers, what brand is it, and do you have a website. Must be a new technology
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
hjcmb
:
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?
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
sparkiedoo
just fit dimplex
problem solved!:D
Or problem created, depending on how you look at it :) :)
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
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
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
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Re: Mitsubishi Ecodans ASHP issues...
Quote:
Originally Posted by
Bigfreeze
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
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Re: Mitsubishi Ecodans ASHP issues...
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 :) :)
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Re: Mitsubishi Ecodans ASHP issues...
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.
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Re: Mitsubishi Ecodans ASHP issues...
They're a bugger for clogging up the condenser alright :D
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Re: Mitsubishi Ecodans ASHP issues...
As Gary would say "airflow, airflow, airflow". How does a banana change the PH, you will have to use titanium stainless condenser?
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Re: Mitsubishi Ecodans ASHP issues...
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
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Re: Mitsubishi Ecodans ASHP issues...
I rang Ecotec about these units, the guy I spoke to didn't know anything about them and said he would ask someone more senior to ring me, he hasn't to date.....................
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Re: Mitsubishi Ecodans ASHP issues...
Jon, don't you know the technology behind these things is so top secret that they can't even tell their customers!!
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Re: Mitsubishi Ecodans ASHP issues...
shhhh, he is not supposed to know about the monkeys
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Re: Mitsubishi Ecodans ASHP issues...
Guys, could this be my problem? The monkey has frozen to death?????
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Re: Mitsubishi Ecodans ASHP issues...
You were probably feeding him too many bananas and the condenser got clogged.
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Re: Mitsubishi Ecodans ASHP issues...
I think t'was the monkeys that installed yours tiredgeek :)
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Re: Mitsubishi Ecodans ASHP issues...
It is all a question of energy in/energy out...the monkeys cannot eat frozen bananas so they throw them at the condenser causing massive damage and since there is no input of energy to the monkeys they freeze to death. BF cannot take his shower and Tiredgeek gets to do a service call but it is a big problem because the monkeys were supposed to be shipped from Ireland and somehow 2 and 2 were not put together as it was a bank holiday so Tiredgeek (TG for short) could not do his service call as the supplier did not have a set of replacement monkeys and BF had cold showers for....ohh maybe 3 or more days as the courier somehow decided it was better to go watch the Isle of Mann TT (he got side tracked). No idea where the monkeys are now.
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Re: Mitsubishi Ecodans ASHP issues...
Comments on the technical aspects of this system are appreciated
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Re: Mitsubishi Ecodans ASHP issues...
Most units in the industry which are market leaders use algorithms which are calculated, this works on compressor frequency, time, outdoor ambient, condensing temperature and more than one sensor on the outdoor coil.
The termination is a combination of head pressure control, coil temperatures and on a wet system peak freeze can also terminate the defrost, peak freeze is a protection which terminates a defrost in teh event the system does not have enough water flow through the plate heat exchanger to stop it freezing.