Hi,
I’m looking for some data for anyone who has an 11.2kw ecodan. I’m in the middle of a discussion / dispute with my installer and Mitsubishi.
Ive got a heat loss of about 11.2kw with and 11.2kw hest pump. So when it’s cold it works very hard. I can defrost 3 times an hour. Im convinced it doesn’t put out 11.2kw when it’s defrosting that much. Has anyone got a system with independent monitoring with maximum output testing.
What model?
The output specified by Mitsubishi is pretty conservative. My 7.5kW unit outputs way more than 7.5. You can check the databook and see what it should output at a given outdoor temp.
When it’s really humid and around freezing temp, it can defrost often. But all air to water heatpumps will do this. It greatly depends on what feed temp you are asking from the unit given the weather.
What you could do is install one of the esp implementations (mines or @f1p) and track the estimated output during an hour an plot the graph (estimates are based on delta T and flow rate).
I think you did purchase back in Feburary - i’m not sure if you captured the data mentioned by @gekkekoe
The computed output power would be helpful, but it is instantanous - where my 8.5kW unit can output over specification for short times it doesn’t appear to sit at this for long periods.
I have been trawling my archived data, my kWh of output heat does over any 1hr period not appear to be more than 7.44kWh for my unit, however the unit doesn’t appear to attempt running at 75Hz+ which is probably because my heat loss is just less than the rating of the unit.
Around 0, during humid conditions, defrosts can be as short as 20min - as it gets colder the air is drier and reduces. Other factors, such as FTC6 firmware 18.0x have been known to have excessive defrosts.
Hi Phil, I did buy something from Melpump back in Feb, is this what you mean? I did install if for a short while but got into a bit of a mess between melcould and melpump and took it out again. But its sitting in a draw still.
@gekkekoe its the 11.2 ecodan. Yeah, I’ve seen it put out 13-14kw at times, but its can’t last long there in humid weather and when its defrosting every 20 mins, its spending 30mins an hour either off, or recovering from a defrost. Its not worth it, so I try to avoid pushing the compressor that hard (102-120Hz).
I’ve had a firmwear update from Mitshi this summer, you think this could help?
Yes, this is what i meant - monitoring the instant output power could be done through this.
To defrost, the unit will work in reverse and remove heat - so bringing your rating down.
Potentially yes, the firmware update may improve your defrosting - but under certain weather conditions as mentioned it won’t be possible to improve ice build up.
I’ll install it again, thanks.
Is the Melpump website yours? If so, I’ve a total life saver. I could not have worked out how to use my heat pump without it.
It’s not my app, but i work with Artur the developer to make the adapters with the detailed info compatible
Reach out to me directly for any support you need
you should monitor for an hour or so, and ignore the peaks, it should give a clear picture. Also plot the frequency, see if its actually running at around 100hz.
Mines never goes there, is your heatloss computed at -10?
the compressor does go up to 120Hz according to melpump when its running very hard. The theoretical heat loss is 11.6 at -3 There was an 800W error on the heat loss survey. I’m hoping in reality its a bit lower. The data I’ve got from last year looks to be in and around 10-11 at -3.
radiators? whats your flowrate
Heat loss is normally calculated here at -10 or -7. So a bit weird to see at -3.
We have 150m2 of UFH, and about 110m2 or rads. In total I’ve about 17Kw of emitter capacity applying appropriate correction factors for rads. It means my flow temps are generally low. The flow can’t get about 35-36, and return 27, so not sure that helps the defrosting.
They run at the some flow temp, no mixing., has LLH but no buffer. I run it all open as I got in a mees when it was zoned. I live in Sheffield, so its pretty rare that its -3 for very long
flow rate is crucial, your delta T is almost 10c… probably low flow rate. Or multizone with UFH at higher flowrate and radiators at lower. Do you have a secondary pump or is everything running on the main pump?
If you are able to increase the flow, then you can decrease feed temp (and thus lower load on the heatpump) but that might be challenging with the radiator part.
Ive got 5 pumps!! Ive got 27l/min going through the primary loop with pump on max. So no scope to increase flow rate. DT tops out at 8 when working hard.
Im mooted the idea of removing the gylcol from system and adding in the anti frost valves to try to reduce viscosity and narrow DT a bit. But my installer not responded to that one. And not sure how much it would help.
Given delta T = 9c, then our output at 27L/m: 27/60 * 9 * 4.2 = 17kW.
Are you sure that those are feed and return temp of the primary circuit? (since you have a glycol mixture, the 4.2 constant will be lower)
I’ve attached the wifi adaptor back in. When I go back into Melpump I now seen to have 2 accounts and display screens. Im currently using summer mode on the original one. which account do I now control the pump with? the new wifi one, or the original?
Ah yes, in MELPump you can merge the two accounts - I think there is something in settings or subscriptions (don’t want two bills either)
Technically, control over either, but only detailed statistics from one
Thanks, Ive emailed them. It’s now randomly heating water constantly and Ive not idea what is actually controlling the heat pump. I now remember why I took it out last time.
I’ll see if they my can sort.
I haven’t had a reply yet, it is holiday season though
There’s a number of 11.2kW heat pumps of HPM: https://heatpumpmonitor.org/?period=all&minDays=0&filter=query:hp_output:11.2:eq:t
However, none of them appear to be undersized so I can’t see any period in time when they are running at 100% when it’s cold.
However, Ecodan are quite good with their sizing, it can probably output close to the rated figure on average during defrosts.
11.2kW is a big heat pump, there’s probably issues with the system design which is resulting in the heat pump not being able to deliver the heat into the house e.g pipe sizing or flow rate. Could you post some photos of your installation?
Also, it would be useful to know the size of your house. An 11.2kW heat pump should be able to heat a 200m2 house with solid walls with no insulation or 350m2 plus for a modern house with wall insulation.
Thanks Glyn. I’ll draw up a diagram later on. I’ve had a look at those Ecodans, it seems like there are all working well within there limits on a cold/humid day. When I defrost 3 x an hour, each for 6 minutes, thats 18 mins an hour its not heating the house. When you factor in the energy taken from the house to defrost and the build back time, my maths makes that not much more than 6kw net gain for the house per hour.
My house is 260m2. I had all the data last winter on melpump, but lost the compressor data by accident when I switched my account to the wifi version. If I keep the compressor down to 90Hx or below i seem to control the defrosts, but when it get 100-120, its game over.
I was reading the Valiant 7Kw issues thread a while ago, and sounds just like mine.