Ventilation systems

[JMAC]

Hi,

I’m new to concept of forums but thought I’d give it a go.

I service MVHR ventilation units and have a particular problem with Heatrae Sadia Advance models.  This model has been replaced by the Advance Plus which looks identical but for a clip on cable connection on the fan assembly module.

Replacement fan assembly modules for failed units should in theory fit both advance and advance plus units but you need to remove the additional clip on cable to allow the module to physically fit into older advance models.  The problem however is that the new fan modules will not work correctly in the older units whether or not you disconnect the cable or leave it connected but uncoupled from the fan module body.  Invariably the replacement unit will work briefly but will eventually switch itself over from low speed to boost speed without activation of a switched live signal and will not return to low speed unless you kill the power supply completely.

Has anyone else come across this problem.  Note, have tried getting advice from Heatrae Sadia and Baxi but they are about as helpful as a proverbial chocolate tea pot.

thanks for listening 

John

[MikeSharp01]

It must be getting a command from somewhere, does the new unit have any unconnected inputs. It may be that noise on these inputs, or indeed the relay input which maybe fed from an output with some sort of pullup / down resistor in the new models controller, is triggering the mode change and latching it. Is there a wiring diagram for both units. On another note I guess you are telling us that Heatrae Sadia don't support 3rd party servicing very well so we should take note! In the light of the right to repair movement(s) I think we should start asking that full circuit diagrams are available prior to purchase of such equipment.

Edited April 29, 2021 by MikeSharp01
Clairty

[dpmiller]

pictures of the fan module and connectors and we might be able to work it out.

[SteamyTea]

Any use?

https://mediacdn.heatraesadia.com/-/media/themes/heatrae/literature/installation-manuals/advance-plus-installation-manual.pdf?v=1&d=20180209T132353Z

[dpmiller]

Hmm interesting. Is there a 3-speed switch installed?

 

Are any RF sensors installed?

[JMAC]

Thanks all for comments, much appreciated.  Just waiting on delivery of a unit now by a supplier who advises that the frost protection sensor which is coupled by a harness to another sensor on the latest models be removed and replaced with old version stand alone sensor.  Will be interesting to see how it goes.

 

In answer to some of above, none of the advance models I have seen in the field are connected to a 3-speed switch but the advance plus models are.

 

The Heatrae manual not really of much help, full circuit diagrams would be nice....

[NOC]

On 04/05/2021 at 18:56, JMAC said:

Thanks all for comments, much appreciated.  Just waiting on delivery of a unit now by a supplier who advises that the frost protection sensor which is coupled by a harness to another sensor on the latest models be removed and replaced with old version stand alone sensor.  Will be interesting to see how it goes.

 

In answer to some of above, none of the advance models I have seen in the field are connected to a 3-speed switch but the advance plus models are.

 

The Heatrae manual not really of much help, full circuit diagrams would be nice....

 

Hi John,

 

I'm in a similar situation and looking at a replacement unit P/N 7035035. It would be a great help if you could confirm if you got the replacement unit to work, and if you needed to swap the frost protection sensor or anything else?

 

In case it’s of any use to anyone else, my failed motor is on a Passivent ihybrid HR1. I've discovered the Passivent was originally made by a company called ITHO and brought into the UK and sold by Heatrae Sadia as the Advance / Advance Plus. It was then rebadged and sold by Passivent for about three years around 2010.

 

Thanks, Niall