Control of Kingspan / Mitsubishi Lossnay MVHR units

[ProDave]

I have one of the Kingspan KAR-50RSDC MVHR units which is a re badgged Mitsubish Lossnay unit.

 

I had a request for information on how I controlled it so am posting it here for all to read and share.

My unit is now in use and fully functional.  Here is what I did:

 

Firstly I don't have the Mitsubishi controller, I just made my own controls based on the wiring diagram on the unit, and a bit of trial and error.

 

Inside the unit there are 2 terminal block for controlling the unit:

 

TM2 has 5 terminals, labelled COM, 1, 2, 3 and 4  This sets the fan speed. If none are connected, the fan does not run.

 

Connecting COM to 4 starts the fan at it's slowest speed.  Connect COM to 3 and it runs faster etc until you connect COM to 1 and it runs at full speed.  What is not immediately obvious is you can connect more than one of the inputs to COM it runs at the fastest of the selected speeds.

 

I wanted a timed boost function, and as it happens I decided I wanted the upstairs (bathroom) boost to run it at it's fastest speed, but wanted the downstairs (kitchen) boost to run it at a less fast speed.

 

So to give a timed boost, I used 2 of this type of boost switch

 

 

They have a 230V switched output so can't directly control the MVHR. So instead each one feeds the coil of  a single pole changeover relay (2 relays one from each of my boost switches)

 

So I have COM permanently linked to terminal "4"

The NO relay contact from the upstairs boost connects from COM to "1"

And the NO relay contact from the downstairs boost connects from COM to "2"

 

 

The other user terminal is TM3

 

This has 3 terminals, one labelled "HEAT", one labelled "COOL" and one not labelled.

I tried both HEAT connected to COM and COOL connected to COM and neither seemed to do anything.  Reading a manual for a similar unit, suggested these control the bypass based on a measurement of internal and external temperature, but with no explanation of the logic used.

 

Then I tried the unlabelled contact on TM3 connected to COM on TM2 and that immediately operates the bypass flap mechanism. Remove the link and the bypass mechanism immediately returns to it's normal position.

 

So I have simply connected a normal switch between the unlabelled contact on TM3 and COM on TM2 and that will put the unit into bypass mode when I wish.

 

 

[joe90]

Thanks a lot for this info Dave, I think I bought the last controller on Ebay (sorry) but only just found that the wiring diagram did not come with it, I presumed the MVHR unit docs would have t but no!. Interesting that my controller shows 1 as slowest and 4 as fastest?

 

 

[ProDave]

Out of interest how much was that controller?  Is it literally just a 4 position switch or are there any electronics associated with it?

 

Can I see the business end of it (i.e the wiring on the back of it)?

[joe90]

Here you go, yes the common for the speed control is teed to the com of the “summer-winter” switch. I didn’t think but I could have sent this before to help you ?.

 

 

[ProDave]

I would guess they intend the "summer / winter" switch to connect to the "heat" and "cool" terminals. But there is no explanation of the control algorithm to open and close the bypass flap, and I dislike not knowing how things work.

[joe90]

Ha, got it working ? however, you are right Dave, speed 1 is fast and 4 is slow ????, I am going to reverse wire it as that defies logic. Thanks a lot mate.

[joe90]

Yup, all up and working, whisper quiet on 1 and blowing a gale on 4!  Even 2 is quite powerful. I have not balanced the system yet just restricted the close room pipes a bit at the manifold. I also have to wire in a humidistat with a relay as this is the way I wanted to control bathroom steam etc (wish I had thought to wire a boost button in the kitchen like Dave.

[Jeremy Harris]

2 hours ago, joe90 said:

Yup, all up and working, whisper quiet on 1 and blowing a gale on 4!  Even 2 is quite powerful. I have not balanced the system yet just restricted the close room pipes a bit at the manifold. I also have to wire in a humidistat with a relay as this is the way I wanted to control bathroom steam etc (wish I had thought to wire a boost button in the kitchen like Dave.

 

You may well be able to add a boost switch using a remote control switch.  The Quinetic system (https://www.tlc-direct.co.uk/Main_Index/Wiring_Accessories_Menu_Index/Quinetic/index.html ) might be an option, all you'd need to add is a 230 VAC relay, driven by the receiver, so that you have dry contacts to switch the MVHR to boost.  It'd mean switching the boost on and off, rather than having the timed function, but that's probably OK for a kitchen.  The dimmer switches are slightly more convenient to use, as they are "click on, click off" when used with a normal receiver, whereas the ordinary switches can, apparently, "forget" whether they are on or off after a power cut and default to off, even if the switch is apparently on.

[Ed Davies]

Pity Quinetic don't do this function anyway as (AIUI) their switches just generate some sort of pulse signal when they transition. That ought to be able to (re-)trigger a timer.  Maybe they do?

[Inchbyinch]

Hi all, 

 

im having trouble terminating the block below. Any advice, solder?

 

r

ed

[PeterW]

Should be a push down and captive connection. Got a photo from the front ..?

[Inchbyinch]

Push hard, got it after thanks. Ceiling in the way so can’t see it from the front. It’s installed in a ceiling void which is a bit tricky to get at

 

Im just using cat 6 for the signals so used 1.5 straps to push it in

[ProDave]

You are missing some of the plastic "push to release" buttons from terminals Com, 1, 3 and 4

 

If you need to release a cable you could try pushing a screwdriver down into the hole where the plastic bit should be

[PeterW]

Anyone who has one of these and needs the manual, its here

[Matt_B]

Hi. I’ve got one of these but in Kingspan form. The circuit board is as-per InchByInch’s. I’m trying to get the summer bypass working but am having no luck. I’ve tried connecting TM2 Com to the last (blank) entry on TM3 (per ProDave’s suggestion) and whilst I get a healthy relay click or two from it, the air remains as if heated through the core. I’ve tried various other combinations on TM3 but to no avail. Can I ask, for those who have it working, do you hear anything positive (like a whirring) from the baffle/bypass motor - i.e. is it obvious to you the bypass has moved into place? Also how quickly does the air temp start to drop after activating it?

 

I note above that PeterW has uploaded a manual for the Mitsubishi-branded variant, but it’s a slightly different manual to my paper one (branded Kingspan). Crucially, the bypass wiring is slightly different. I’ll upload it when I get chance in case it helps others.

 

Anyone any ideas what to try next? Without clear unambiguous instructions (my manual is poorly written) I may have to wait until Winter when the loft cools and strip it all down to see what’s going on.

[ProDave]

Hi Matt

 

I would be interested in seeing a picture of your circuit board and connections.  I have seen 2 different versions but as yet only seen one version of the manual, and my circuit board differs to the one in the manual.

 

When I activate the summer bypass with the undocumented connection as you have tried, I hear a click, followed by a whir whir for a few seconds as a small motor moves the bypass flap to the bypass position.  And when you deactivate it, the same click, then whir whir for a few seconds as it moves back.

[Matt_B]

Thanks for the quick reply Dave. I hear the click but alas not the whir whir... I’ve had the thing installed now for 10 years and it’s always been stinking hot in Summer. I thought it was due to the intake being on a south-facing wall, but I’ve gone to the trouble of moving it to the west and it’s no better, hence my review of the wiring. I’ll have to keep trying different combinations. Worst case, I’ll rig up a temporary (external to the box) inline duct fan and route the intake direct to the to supply, bypassing the lossnay altogether for this summer for the inflow, and then revisit when it’s cooler up there in the loft.

 

I’ve just scanned my paper manual doc and will attach. It’s the one which came in the box when I bought it. Hope it helps. 

2020-04-26_134952.pdf

 

Forgot to add, in terms of circuit board, it’s exactly as per InchByInch’s. I’ve a 4 position rotary switch wired via cat6 wire to the airing cupboard. I keep it on the lowest speed in Winter (trickle) and the next speed up when it warms up. It’s a largeish house (4000 sq ft) - albeit it’s piped to upstairs only - and I never need the higher speeds. Wiring for the bypass is via the same cat5 to a toggle switch, but as far the lossnay end of things..well, I’m struggling with that as above :).

Edited April 26, 2020 by Matt_B

[ProDave]

Thanks.

 

That's the "missing manual" that covers the version that I have.

 

The bypass control terminals as shown uses two inputs called "heating" and "cooling"  I could not get mine to do anything with those.  If I activate either, nothing happens.  I assume it does some sort of automatic control but I have never seen it explained what or how.  It was only by experiment I found that the "not used" terminal activates the bypass manually and instantly.

 

If you get the click but not the whir whir I suspect something is broken, or just stuck?  It might be worth taking the lid off to see if you can get at the mechanism, see how it is supposed to work and see if anything is obviously stuck.

[Matt_B]

Yes, exactly - I think that’s my next step. The manuals are just so poorly written though that it’s hard to know how to connect these things up. Anyway, glad the manual helped. If nothing else, it’s up on the web now in case I lose my own copy.

 

If I get to the root cause I’ll post an update. Just need to get through another sweltering summer (with full heat recovery in operation!).

[MJNewton]

On 26/04/2020 at 14:21, Matt_B said:

If I get to the root cause I’ll post an update. Just need to get through another sweltering summer (with full heat recovery in operation!).

 

Note that if it is warmer outside than in then keeping the heat exchanger 'in loop' will cool the incoming air as heat will transfer to that being extracted/exhausted. Your bypass should therefore not be activating in such a scenario.