Adding outdoor reset to Munchkin 140M

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Old 02-24-10, 10:22 AM
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Adding outdoor reset to Munchkin 140M

2200 sq ft residence, converted gravity with cast iron radiators plus second RFH zone, Munchkin 140M, about 4 years old with 925 control panel and no Vision control built in.

I want to add outdoor reset. This winter I have been adjusting the setpoint manually and steady condensing is great. So I have an approximate reset curve to start with, but I tire of adjusting it manually a couple times a day. Buying/installing the proper control boards *may* be the best way to add reset, but I don't know exactly what is needed (926 board? Vision 1? Vision 2? software?).

The tech who sold me the boiler seemed to do a decent job on the piping p/s etc (although hot outlet goes straight up w/no trap) but oversized the boiler, botched the intake/exhaust install so it drew flue gases for 3 years until I figured that out, the wiring was not up to code, maybe a few other issues. I'm glad they sold me one but they didn't know much about mod/cons, they just set it to 180 told me I might want to lower it if the boiler short cycles. This year I really dug into it; I have never run it more than 135 and it spends almost all of its time in the 120s. They never recommended annual service (!), even after coming out a few times and replacing the blower under warranty (another story ...).

Anyway all of that is just to say I have learned a lot about this boiler and won't move on this until I understand well what I want/need, hopefully I can just install this myself. I have done a fair bit of service on the boiler now, so have a good source for Munchkin parts, seems I can do most things except dial in the combustion.

suggestions on the reset?
 
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Old 02-25-10, 06:17 PM
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I think I might start off following the yellow brick road to Munchkin land... and ask the Wizard what's available for your boiler. Then go from there... let us know if you get anywhere with them, and pay no attention to the man behind the curtain.
 
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Old 02-25-10, 06:27 PM
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Yup. Call HTP. IIRC, they made some changes in ~2006 that might dictate one version of their control over another.

You might also be able to use a 3rd party control, like a tekmar 270. But you'd need to make sure it can interface/override the Munchkin MCBA.
 
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Old 02-25-10, 10:57 PM
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Well I called tech support twice yesterday, twice today. Each time I spent 30 minutes on hold before I was rolled to voicemail. Did not leave voice messages. I guess it is a busy time of the year.

I also sent email request for info from their website. From that I did get a reply, telling the part number (Vision 1 kit # 7250P-622) based on the serial number of my boiler. I also asked if they recommended an upgrade to a 926 controller they said "not required for this upgrade." Looks like I can get the Vision 1 for about $160.

I'm feeling like I need to get them on the phone, see if I can get more info about the installation. I am trying to follow up the email we'll see where that goes.

Looks like the tekmar 270 runs a lot more $$. Compatibility issue aside, is there any big advantage to it or another 3rd party?
 
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Old 03-09-10, 01:24 AM
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The Vision 1 Kit for my boiler is $170. It is a retrofit kit, Vision control is now standard on all their mod-cons. I looked closely at the installation manual. The kit consists of an outdoor sensor and its 2 wires, an indirect tank sensor and its its several wires (including for the pump on the indirect), and one wire to serve as hot for an optional remote failure indicator. I have no indirect so all I really need is the outdoor sensor and its 2 wires. The sensor alone can be had for $60.

Am I OK buying only the sensor and carefully attaching it with the recommended AWG18?

I would like to source proper connector ends for the 2 wires at the Molex plug, ideas? E.g. I can buy wires made to fit a different hole in the Molex for $6 each, and will do it if that is recommended, but seems excessive. Need a junked Munchkin boiler for its wire ends ...

Any comments would be welcome.
 
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Old 03-30-10, 08:24 AM
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Just a wrap-up:

For my older Munchkin with 925 control board, and no indirect hot water setup, to add ODR (outdoor reset) the only relevant parts in the Vision 1 kit are the sensor and the molex wire end connectors. Everything else is already there at the boiler.

So I purchased just the sensor, plus the correct wire ends from Mouser Electronics - Electronic Component Distributor for the existing molex plug in the boiler (took some research to find but then $0.50 each), installed the sensor as per the Munchkin manual and ODR seems to be working well.

I specifically asked HTP if they recommend upgrade to a 926 control board and two different techs said that if the 925 is working, don't mess with it. If I later install a 926, the ODR setup is no different will swap right over.

Beer 4U2
 
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