Baxi duotec

[Andygasman2010]

Another one for the CC forum i'm affraid but my application is still pending.

Anyone come accross poor hot water from this boiler? It's litterally a few days old and never been right. All basic checks are ok but it's still really poor hot water. Baxi have been out but i was a little suspiscious as the guy didn't really seem to know much, he said it was normal and down to low incoming water temp. I'm going to double check all the basics on friday then get baxi out again if it's not right.

During hot water demand, does the display show primary temperature or domestic temperature?

I've not been there personally, it's an install of one of the guys i work with. I just want to go there on friday fully armed with info, thought there might be a known problem with this boiler. I'm not a fan of it myself.

 

[powell30]

Primary.

And check if the diverter is letting by the cartidges sometimes stick if they have been lying around in the warehouse. Remove the diverter head and check the pin moves in and out. I assume the gas valve has been checked and fga used?

Also make sure you check the obvious, cold water temp in, temp out and flow rates of water

 

[Andygasman2010]

Primary.

And check if the diverter is letting by the cartidges sometimes stick if they have been lying around in the warehouse. Remove the diverter head and check the pin moves in and out. I assume the gas valve has been checked and fga used?

Also make sure you check the obvious, cold water temp in, temp out and flow rates of water

Thanks for that.

The primary temp doesn't get above 60DegC during hot water demand, that's why i was confirming what temp it was actually displaying. It's a collegue that's been dealing with this problem, i'm going there on friday so i'll be doing FGA/gas rate/temp checks personally. I'll be checking the diverter now too!

thanks

 

[rojaca]

It may be likely that the dhw thermistor is misreading. The pcb does check the resistances on the thermistors and if they fall outside a set range it will show a thermistor fault code. If you phone Baxi technical they will be able to give you the reistances expected at a range of temperatures

Other than this check your temperature rise against flow rate.

 

[Andygasman2010]

It may be likely that the dhw thermistor is misreading. The pcb does check the resistances on the thermistors and if they fall outside a set range it will show a thermistor fault code. If you phone Baxi technical they will be able to give you the reistances expected at a range of temperatures

Other than this check your temperature rise against flow rate.

Well it's not fell out of range as no fault code has been displayed. I'll have a new sensor on my van so i'll plug it in loose (so it constantly reads high resistance/low primary boiler temp) and see what happens. same for the DHW sensor.

 

[rojaca]

sorry should have been clearer.

The thermistors can register a higher/lower resistance than what they should, but still be within the range that the pcb is looking for. In this case the dhw one. In turn causing the pcb to modulate the boiler down to regulate the dhw at the temperature at the setpoint of the potentiometer. Hence the low reading of the primary water temp.

Potentiometers on the duotech are a different part no. from the other used in the "spa" range (e.g 105's, performas etc).

 

[Andygasman2010]

I'll have a new sensor on my van so i'll plug it in loose (so it constantly reads high resistance/low primary boiler temp) and see what happens. same for the DHW sensor.[/quote]

Thanks, i'll do this test as described.

 

[Andygasman2010]

Correction on that boiler, it's actually a Main 30eco and not the Baxi Duotec i thought it was. I've not been involved with it personally until today. Anyway, all my checks/test are ok and as per manufacturers instructions, except the gas rate was 2kw short. 28kw in stead of 30kw. Not sure how much of a difference this missing 2kw would make....

I think maybe it's the customers interpretation of "hot water" and expectations have not been met, they had an indirect cylinder before. Also the boiler takes quite a while to reach temperature. I'm thinking this maybe just isn't a very good boiler too!

I had a temp rise of 44DegC at 10l/pm (pretty good i think)

Any thoughts....?

 

[rojaca]

1. did you obtain your gas rate with the boiler in commissioning mode? Running the dhw will simply modulate blr down
2. The flow rate/temperature rise you should expect are in the technical spec in the m.i.
The hydraulics of the boiler differ very little from the duotech etc. Only real difference is the primary heat exch' is alloy and the fan configuration.
TBH quite reliable blr with very few problems experienced.

 

[Andygasman2010]

Thanks for everyone's advice. i didn't check the as rate in combustion test mode, i didn't know it had one! I didn't think it would be modulating when i was checking it as the hot water was pretty poor and primary temp was quite low.