If it's accessible then it should be fine. The cylinder won't get even warm on the outside.

Mine is in the loft which was annoying for about 3 weeks. Now mine is optimised I probably won't touch it again for weeks/months.

If it's accessible then it should be fine. The cylinder won't get even warm on the outside.

Mine is in the loft which was annoying for about 3 weeks. Now mine is optimised I probably won't touch it again for weeks/months.

Posted by: @bash

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We've started our Heat Pump install today, a busy day.

One question I wasn't expecting , the location of the Daikin MMI.

They have offered to attach it to the front of the hot water cylinder. I didn't know you could do that.

Is it a good place for it to go, or should I look to get it placed elsewhere in the cylinder cupboard?

Thanks.

Personally I wouldn't without first being certain this makes sense. Nor would I have it in the cylinder cupboard.

Chances are its got a room temperature sensor in and, if it has, you may want to use this unless you are operating in pure weather compensation mode throughout the season, which you cant really know until you have tried it.

The exception to this would be if, like my Vaillant, it has two MMIs, one designed principally for commissioning and the other for day to day operation.  In this case the one designed principally for commissioning can of course go in the cylinder cupboard assuming that the temperature sensor is in the other.

@bash, if you’re planning to use any form of load compensation, as @jamespa has also mentioned, I’d be careful where it goes. In our case the MMI was put inside the utility room cupboard with all the pipework and cylinder, and that space was permanently 24C+ because of standing losses. As a result the controller never saw a realistic indoor temperature, so load compensation was never available to us as a feature.

The MMI can physically be mounted on the front of the cylinder, yes, but whether it should be depends on how the system is being controlled. If it’s acting as a room reference, putting it in a warm cupboard full of pipes will skew everything. The heat pump will think the house is warmer than it actually is and back off when it shouldn’t, and that will be probably be disabled as a feature by the installers. I’ll caveat that by saying that this is obviously only relevant if Daikins have some form of load compensation, which I assume they do.

If you’re not using load compensation and it’s just there as a user interface, it’s less critical. But if LC is part of the design, I’d be pushing for it to be in a representative living space, or at the very least somewhere that tracks the actual internal temperature of the home, not a heat-soaked cupboard or space.

@editor 

Thanks Mars.

The additional room thermostat (hard wired) won't be in the boiler cupboard, it'll be in the lounge, but will be connected to the MMI.

Does the MMI have and additional thermostat, I'd assumed it wouldn't?

Posted by: @bash

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The additional room thermostat (hard wired) won't be in the boiler cupboard, it'll be in the lounge, but will be connected to the MMI.

Is that a Daikin one or a third party one and what will that be used for?.  In general you want to use external controls/thermostats only as limiters not controllers, or better still not at all.  Also if you are going to have an external thermostat it must not be of a type that tries to be 'smart' by modulating the heating on/off as it approaches the target temperature.  In most cases third party stats are best avoided unless there is a specific reason to have one (unlikely) as they provide only crude information to the heat pump relative to the inbuilt temperature sensor in most controllers.

Posted by: @bash

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Does the MMI have and additional thermostat, I'd assumed it wouldn't?

I dont know about Daikin specifically (I will try to find out and @editor or @toodles may know) but the vast majority of controllers do have an internal temperature sensor and in almost all cases if there is one it should be used in preference to a third party thermostat because it tells the heat pump much more information.

Basically the message is, unless there is an exceptional reason or the Daikin is atypical you should not be fitting an external thermostat and one  Daikin controller should be in a representative room. Note that, as I mention above, there may be 2 DAIKIN controllers one of which is basically for commissioning and the other for user control, and the latter needs to be in a representative room.

@jamespa I can confirm the Daikin has the modoka or however they spell it. My Daikin is set to LWT and  only functions as a thermometer.

Posted by: @jancold

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@jamespa I can confirm the Daikin has the modoka or however they spell it. My Daikin is set to LWT and  only functions as a thermometer.

@bash  That confirms it.  The Madoka or equivalent (I think there is also another older generation device looking something like the below) should be in a representative room; strongly recommend no third party thermostats.  Please dont let your installer fob you off with a third party thermostat as the only thing in a representative room.

@jamespa 

Thanks.

They aren't fobbing me off thankfully (they have been brilliant so far).

The Daikin comes with the controller and a hard wired room stat.

We will only use the Daikin room stat as a limiter in case we overheat, as all our rooms are south facing.

The Daikin room stat should only trigger if we get a really sunny day.

We had a good sunny day a week or so ago.

It was -3 outside, but was 23c in the living rooms, so our gas boiler (flow temp set at 50c) switched the whole system down, then kicked back in early afternoon when the sun went down. The house was lovely and warm all day long running at 21c 24/7.

The controller (I can never remember if it's Maduka or MMI) is what they suggest to attach to the cylinder so it's easy to access.

This is the controller (MMI) and what they will install on the cupboard (image taken from another post).

This is the hard wired room thermostat, to go in the lounge.

Posted by: @bash

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@jamespa 

Thanks.

They aren't fobbing me off thankfully (they have been brilliant so far).

The Daikin comes with the controller and a hard wired room stat.

We will only use the Daikin room stat as a limiter in case we overheat, as all our rooms are south facing.

The Daikin room stat should only trigger if we get a really sunny day.

We had a good sunny day a week or so ago.

It was -3 outside, but was 23c in the living rooms, so our gas boiler (flow temp set at 50c) switched the whole system down, then kicked back in early afternoon when the sun went down. The house was lovely and warm all day long running at 21c 24/7.

The controller (I can never remember if it's Maduka or MMI) is what they suggest to attach to the cylinder so it's easy to access.

 

I think the one in the cupboard is the MMI and the one that looks like a thermostat the Madoka.  The Madoka is described as a wired remote controller so I presume its actually a temperature sensor plus possibly some more functionality.  Doubtless all will become clear

I am sorry for the 'fobbing you off' comment, many people who come here have been fobbed off so there is natural suspicion and its easy to forget that a large number of installations go very well!