Laars boiler Outdoor temp sensor

ColdHouse · January 16

I have a Laars Mascot FT that is about seven YO. The other day house was cool when I woke and checked Laars and boiler temp was down to its lowest set temp because the sensor said it was 20* warmer than it actually was. I temporarily reprogrammed the high and low temp boiler set points used to modulate according to the outdoor temps, which brought my water temp back up.

The sensor maybe going bad or maybe poor placement, but until I get that sorted out, can I just disconnect the outdoor temperature sensor? If so, will it default to a certain temp or will the boiler fault out and not run?

EBEBRATT-Ed · January 17

with some boilers in general disconnecting the outdoor air sensor will force the boiler into full heat because the boiler will think it is -20 out or some low temp. The boiler should cycle on its high limit control.

If you check the boiler manual, they will usually find a table that will give you ohm readings for the OA sensor based on the temperature it senses.

ColdHouse · January 17

thanks @EBEBRATT-Ed for helping. I will look at the manual for the ohm reading and check if I can find it.

If I disconnect it, you think it will go to the programmable/max temp. I currently have that set at 140* for my radiant floor system. If that’s the case, it wouldn’t be a bad thing for me to run that high because of the extreme cold snap coming my way and why I want to get it figured out prior.

GroundUp · January 17

Yes, you can disconnect it and it'll just aim for its commanded setpoint. The factory setpoint on the Mascot should be 140* but it can be easily adjusted in the settings menu.

hot_rod · January 17

It depends on the boiler control. Some will ask you if the outdoor sensor is being used, other just recognize it when connected.

With the ODR disconnected you need to program in some max temperatures or the boiler goes to factory default. The manual should tell you default settings.

To test a sensor you need to know the temperature where the sensor is located, so a thermometer is a good idea.

If you have an icicle or ice cube, putting that against the thermistor it should red the 32° resistance.

An example of a sensor temperature/ resistance chart

Outdoor sensors need to be located out of the sun and where it cannot be influenced by reflection, exhaust fans, etc. Often tucked up uder a roof overhang is a good, protected location.

But if it has worked properly in the past, location should be ok?

ColdHouse · January 17

The manual says the default setting for “16:cH - Heating maximum temperature” is 180*f . I currently have that set at 140* max and 120* for “17:cL - Heating minimum temperature”

the other morning it was around 10* and boiler said it was 27* on the outdoor sensor, and running at the minimum set point.

ColdHouse · January 17

@hot_rod thanks for helping. I will need to check the resistance. Wish you lived near by, I’d love for a whole system look over and possible redesign. We absolutely love the radiant floor heat, as I sit typing, I can feel the nice warm floors.

I very unfortunately in 2001 fell for the “Do it yourself” radiant system from Radiantec of Vermont many years ago and have regretted it since. I hashed over that all with the forum last year. I used to heat with the Polaris 100k BTU hot water tank and had no problems with it until it quit after 15 or os years of service and more $ to repair then to replace. Plumber Freind suggested the Laars. I’m 7-8 years in with the Laars and have near zero confidence in it.

I have spent a 40 year career as an Industrial Electrical Mechanical maintenance person and have done 99% of all my own fixing and building my entire life.The high tech nature of the Laars is challenging and Im now reaching a point I would like to have a solid, reliable locally available tech to service the Laars, but finding it difficult to find. Plumber Freind laughed when I asked who is best to trouble shoot and repair the Laars and replied me….. I went onto Laars web site to search by location contractors. The had them listed in different tiers, from bottom being installers an then owing up suggesting factory trained contractors. The only one listed was a 30 mile drive, so I went and had a face to face with him. He said they stopped installing the Laars years ago from numerous problems and said they were just purchased by I think Wiel McClain? He didn’t not exude the confidence I was looking for in a Laars repair people and said they didn’t carry parts… The reason I mention all of that, is to ask, how do I find the right tech? I live very rural in a small town 2.0 hours from major Cities and 30-45 minutes from a small City. Because our winters here can be terrible and cold, below Zero and then summers where we can have weeks of high humidity and temps in upper 80’s -90’s, most all houses here are all forced air. Very few folks I know have any knowledge of hot water heat let alone radiant floor.

How to find a reliable tech for Laars in a hot water heat desert?

hot_rod · January 17

the Mascot has gone through mss as my renditions The early oner were actually Baxi 330’s coil type hx. The use a few different versions of a Kiturami fire tube design, I imagine a few different control platforms

It would be a diehard installer that is knowledgeable about all the different versions

If you find a rep that has been with Laars for 20-30 years and a hands on troubleshooter that would be sweet

I think this patten is consistent with most mod con boiler manufacturers. They follow trends and the supply chain. Sermeta formerly Gianoni (sp) is still supplying coil water tube designs that dates back to the 1990’s!

I see they have a booth at the upcoming AHR Expo in Vegas

ColdHouse · January 17

@hot_rod my Laars was bought new ad installed February 2018, so eight years old next month.

Do I look to find the local distributor of the Laars and ask them who they would recommend? Or is there another method to find a knowledgeable service company?

hot_rod · January 17

If you are supporting and buying from a local supplier, start there.

If not the area reps generally know who the best qualified installers and techs work for.

Laars boiler Outdoor temp sensor

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