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  1. #1
    Join Date
    Dec 2012
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    Need help identifying my heating system(s?)


    I recently moved to upstate NY and am trying to figure out what kind of heating system(s?) I have. I'll walk you through what I know (or think I know) and please let me know if this is correct or if you have an advice.

    "Outline.png" is a basic outline of my house.

    First, I don't have central air - I have window units.

    In my basement I have a hydronic gas boiler. This can be seen in "boiler.jpg" and "hydronic.jpg".

    On my first floor I have two Honeywell thermostats, each one controls baseboard heaters as shown in "1st floor.jpg".

    When I open these thermostats, it looks like what is shown in "Honeywell Thermostat innards.jpg" - there are two wires connected to the "R" and "W" terminals. I assume this means it is single stage heat, low voltage. I measured the voltage between the R and W terminals and I got 28.6VAC (not VDC?).

    Now, up on my second floor I don't have any Honeywell thermostats - instead I have a bunch of these old Eaton Mears M401 thermostats, as shown in "Mears M401.jpg". There are three wires running into the M401 - ground, black, and red (I know color means very little). I didn't measure their voltages. I believe these are only used for line voltage electric baseboard heating? So this means all the zones my second floor are electric, not gas? Or could they have run the copper pipes from the basement up to the 2nd floor baseboard heaters to the boiler but left the old thermostats? That doesn't make sense but is it possible?

    It looks to me like I have two different heating systems - gas on the first floor and electric on the second. Since gas is cheaper I take it this means I should rely on my 1st floor heating and let the air rise to heat my 2nd floor as much as possible.

    One last question - if I want to upgrade the M401 thermostats on the second floor, I would need to buy line voltage thermstats for electrical baseboards, right?
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  2. #2
    Join Date
    Sep 2003
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    Looks like the honeywell stats may control each of the pumps in the picture
    Turn a stat on a call for heat and the boiler comes on and also one of the pumps to heat it's respective zone.

    I am not familiar with the other t-stat. And since you didn't include a picture of the upstairs radiators or are they fan coil units? (radiator with a Blower attached) radiators. I guess the easiest way to tell if the boiler helps heat the 2nd floor, just turn off the power to it for a short time and turn up the t-stats on the 2nd floor and see if you have heat or not there.

    Additionally You may have other fish to fry.

    The black pipe coming off of the top of the boiler in your pic looks suspiciously like a recalled plastic plexvent pipe. There is program still in effect to get you some money to help you have it replaced by a contractor.

    Not as much as originally when the program was in full swing but every little bit helps

    here is a link to the remediation program

  3. #3
    Join Date
    Dec 2012
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    Thread Starter
    small change,

    Thanks. That's been really helpful. Knowing those are pumps attached to the boiler, it now makes sense to me how the two Honeywell thermostats control the heat that reaches the two zones on my 1st floor. I was missing that piece of the puzzle.

    Written on the service log, in Sept 2010 a technician writes he will price out the cost to replace the Plexvent II but apparently the previous homeowner chose not to get it fixed. The Plexvent II is stamped it was manufactured in 1995 so I'm pretty sure this pipe falls under the recall. I'm disappointed that three service calls in the last four years by two different techs and the homeowner wasn't motivated enough to fix this. And my homeowner's inspector didn't catch it either but since he isn't an expert in HVAC I'm not too surprised. In your opinion, is this recall well-known enough he *should* have known about it? The HVAC tech who serviced this boiler was even from one of the companies listed on the CPSC website as participating in the replacement program.

    Until I can call the 1-800 number and get this fixed I moved a CO detector into the basement (have them on 1st and 2nd floors). Its reading 0 ppm so far...

    Thanks again for catching that Plexvent II issue.


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  4. #4
    Join Date
    Sep 2003
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    I read all the service stickers when I check out a heating or a/c system for the first time.

    I would think the Home Inspector would do the same thing when he is inspecting
    it also.

    I don't know what a phone call or a letter to the home inspector would get for you other than some satisfaction butI would certainly ask the Home Inspector about it since
    The Boiler service sticker specifically mentions it

    But that's just me

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