Mitsubishi Ecodan ASHP general set-up and efficiency - Air Source Heat Pumps (ASHPs)

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Mon, 13 Jan 2025 08:40:46 +0000

@gary Morning, yes, both of these are set to 3 on physical pump but also on the FTC. I think I've upped the speed to 4 on the FTC just to see if it made a difference.

I think you're correct on the outside temp causing the issue, it's been -7 the last week and it seems to be the defrost kicking in that drags down the DHW tank temp. Even at the best of times the HW tank only stays in the 40's for a few hours.

Thanks,

Neil

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

Gary — Mon, 13 Jan 2025 08:19:53 +0000

@ngillam Depending on your controller the pump speed for the HW can be controlled in 2 ways newer versions have pump speed in the service menu for both hot water and heating you can set a different speed for each pump. I can't find an image of that menu but if you have an older controller then the pump speed menu just looks like this. This only controls the speed of the primary circulation pump.

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If you have this version then you have to manually change the pump speed for the hot water tank on the pump by flicking the switch, should look something like this. The switch should be set to 3.

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Apologies if you already checked all this but with both HW and circulation pumps set to 3, I just wanted to check you understood it correctly.

If this isn't set to the highest speed this could be the issue, if not, I do think from what you have described then you have a hot water recirculation circuit that is cooling the hot water and at these outside temps the HP just isn't capable of heating the hot water.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Mon, 13 Jan 2025 07:19:50 +0000

@harriup Morning, yes, my pump speed is 3, flow rate of 9 off the top of my head. does that seem OK? My issue is the fact we've struggled to reach 47degs whilst defrost cycle kicks in. This means us both having to wait between showers for reheat, never been an issue before, appears to be the defrost disrupting heat and drawing down HW tank temp.

Thanks,

Neil.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

HarriUp — Mon, 13 Jan 2025 00:05:07 +0000

Have you checked the pump speed in the settings menu for the HW cycle? And maybe check the flow rate while the HW cycle is running. The defrost cycle looks to be taking a long time to get going.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Sun, 12 Jan 2025 18:52:34 +0000

@gary Agreed, installer needs to look. I did up the operation time to match schedule but it's still struggling to reach temp and it still switched to heating.

Thanks for your help, enjoy what's left of your Sunday. I do owe you pints if ever you venture to my neck of the woods.

Neil.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

Gary — Sun, 12 Jan 2025 18:03:00 +0000

As I said in a previous post your max duration is set to 90 mins you need to change it to at least as long as your schedule if you want it to heat for that length of time

I think you need to get your installer back something isn’t right.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Sun, 12 Jan 2025 17:58:02 +0000

@gary It's already on Std , it was one of the things I checked earlier, I've been watching it for the last coupe of hours, it's just paused the DHW heat at 40 degs and switched to heating despite the DHW set to run for another hour according to schedule!! Really confused now! I can't get it above 40ish, even when I force it using the FTC function.

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RE: Mitsubishi Ecodan ASHP general set-up and efficiency

Gary — Sun, 12 Jan 2025 17:29:06 +0000

The only suggestion I have is there is an eco and std setting for HW heating, if it’s on eco change it to std it will make the HP worker harder for the HW cycle

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Sun, 12 Jan 2025 16:46:39 +0000

@gary The HW schedule has kicked in for evening showers, despite the timer for pump set to 24hrs the pump has auto switched off for the hot water heat. It's taking it's time heating though.......

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The UFH timing and pump are still running.....thoughts?

Thanks,

Neil.

RE: Mitsubishi Ecodan ASHP general set-up and efficiency

ngillam — Sun, 12 Jan 2025 15:18:13 +0000

@gary Will give it a try, thanks Gary.