MVR Stat

[Rekusu]

What ho one and all,

I have a MVHR unit in the loft and recently, when it starts, the Alarm light is illuminated. The manual says that the incoming thermostat needs manually resetting but this involves clambering into the loft every time. I want to replace the stat but as it is a Swedish unit, they will not ship the part to the UK.

I is a 16/250AV Normally Closed 80C, manual rest stat but the base has a smooth shape that allows it to fit flush into the incoming air flow.

However, I have found many that will fit but they all have a base which will not fit flush in the hole, although the stat will fit in my MCHR unit as the bracket dimensions are the same.

The second photo is a typical example of what I have found on the net.

First question; why does all my Google searching only find stats that look like that second photo? Cannot find anything that resembles my current stat base. As the second will fit but the face will not protrude into the air flow, am I likely to encounter any difficulties?

Secondly, it appears that the most common stat is 10/250AC but my current is 16/250AC. What happens if I fit a 10/250AC?

Third photo is the current stat. Where can I find a stat like the existing one?

Thanks and toodle pip

Rex

 

[Adam_151]

Secondly, it appears that the most common stat is 10/250AC but my current is 16/250AC. What happens if I fit a 10/250AC

That will of course depend on what load is being drawn through it, if its less than 10A then it'll be fine, if more then it'll be overloaded, and once would hope that the excess heat generation just feeds back into the thermal element and causes it to keep tripping, rather than get hot and smoky

I assume that this is a MVHR with a heater battery given its got an air overtemp cutout? what is the load of the heater bank?, and I assume the thermal cutout just disconnects the heaters, and leaves the fans running in order to dispate the heat from the over temperature condition?

 

[jj4091]

This company suggests they can supply a stat that meets your spec. You will need to message them. https://www.ebay.co.uk/itm/30486205...zs1f3X8dIk6tBhT5c%3D|ampid:PL_CLK|clp:2047675

 

[Rekusu]

Thanks for the replies. Yes, it does have a heater battery, I guess to pre-heat the incoming air if the outside is too cold. But it is tripping during the current 'summer' months and giving an alarm indication,the fans not working, when obviously, the incoming air cannot be too cold. Once reset, the MVHR unit works fine.

The attached pdf is the instruction manual. I have the L4X which is fused at 10A with the L7X fused at 16A. However, the manual rest thermostat that seems to be the problem (I believe that to be the problems, as once I have the alarm and not fans, resetting the stat and pressing the rest buttons on the control panel, and everything is fine (until the next time!)

I have red arrowed the location of the stats.