Digital Programmable thermostat for home - single pipe steam system

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afjes_2016

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Digital Programmable thermostat for home - single pipe steam system
Thermostat controls only heat, no A/C.

I would like to replace my manual mercury thermostat for my home heating system. I have single pipe steam. Small home so I guess it is only one zone if that applies to this topic.

The thermostat cable that is used is using two wires going to the steam boiler. There seems to be more wires in the cable but not being used. I traced the cable that connects to the steam boiler and see that only two of the wires are actually being used. I am a bit hesitant in disconnecting the thermostat from the wall to see how many wires are connected to it but I would think there would only be two wires in the back of the thermostat. I don't really want to pull it from the wall until I am ready to replace it and have the new unit in hand. I will pull it from the wall if I have to in order to be sure I buy the proper thermostat.

There are so many available on Amazon I just have no idea what I am looking for when browsing.
I want one that I can program. Preferably one that has 7 days. I don't want one where it is only one program feature where a week of Mon-Fri is controlled by only one program. I would prefer that it can program all 7 days independently if possible.

I am thinking that I may want one which is WiFi capable but I am not sure until I see the diff in costs if it will be worth the extra money for it.

The problem I have also now is that the temp diff from what the manual therm is set at can vary up to 8-10 degrees before the boiler kicks on or off. So I either freeze from the cold before it kicks on or I die from the heat before it kicks off as it cycles. I believe there is a setting I can adjust but it is so old I really don't want to mess with it and just replace it. More important that I can program that continue to use this manual one.

When I browse on Amazon what should I be looking for so I know it will be compatible with my steam boiler system?

Thanks
 

kok328

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Until we find out how many wires are on the back of the t-stat and what they control, nobody really knows.
Most programmable stats require a common wire which you don't have so upgrading the stat does not look promising.
 

afjes_2016

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Two photos attached

Note: The wires red and green originating from the thermostat transition to red and white at the boiler. Transition point Red to Red - Green to White. I guess they did not have enough of one and subbed another cable in there. The transition was only about 18" above where it connects to the boiler burner.

Kok328 - you say upgrading the therm to programmable requires a common wire which I don't have. What do you mean by a common wire? Also, I can run another thermostat cable if need be. The routing is not hard to run a new cable. I just need to know what type of cable to purchase and where to make the connections especially on the boiler burner as the pic shows just two screws on the boiler burner.

Are you saying that if I keep the present therm cable I can't use a programmable at all or that my choices are gong to be very limited in the choice of a programmable therm?
 

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kok328

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your cable has extra wires in it as you mentioned but, this is of little help as it is the boiler itself does not have a common/neg (negative in DC, neutral in AC) connection thus prohibiting a programmable tstat.
 

afjes_2016

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If I can't use a programmable stat can I at least get a digital one?
 

Eddie_T

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I think programmable is possible but I don't see enough wiring for control of a boiler in your pictures. I can't help you but I would go to youtube and see if there is a mercury switch replacement video that addresses your situation. Otherwise you may have to involve a HVAC tech.

Here's a sample but prolly not your answer · · ·
 

afjes_2016

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Thanks Eddie_T.

I'll check out some you tube videos and see what they come up with. I am going to stick with the "Ask this old house" and other ones like it so I know they are doing things properly. I don't trust some of the DIY videos out there. Especially when I watch ones for home electrical - me being a retired electrician I shutter at some of the DIY videos out there as to how dangerous or incorrect they are.
 

afjes_2016

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Thanks Hamberg - It seems that I am already a member on that forum from years ago but have not posted in quite some time. I am just a bit hesitant about posting my issue there for the reason that I know the members on this forum much much better and trust their judgement. Not that the members on the other forum don't know what they are talking about but it is just my comfort zone.

That forum has on the main page (see snipit below) an advertisement to find a heating contractor in my area. I am concerned that by posting on that site I will end up with answers from persons trying to get my problem as their job by contacting me.

1634232680215.png
 

Hamberg

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Thanks Hamberg - It seems that I am already a member on that forum from years ago but have not posted in quite some time. ..
Yes, same here. And, same on a bunch of the forums; I find you need to show them you have a "reasonable" grasp of the base-subject material before they will (willingly) share knowledge.

I only know enough HVAC to get into trouble! :O) One other possibility, and not sure why I didn't think of this before, would be to call Honeywell directly. I've had their tech and engineers guys on the phone a few times and they were always willing to help.
 

afjes_2016

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Yes, same here. And, same on a bunch of the forums; I find you need to show them you have a "reasonable" grasp of the base-subject material before they will (willingly) share knowledge.
And this is what I like about this forum. More DIY friendly for sure. I mainly help out in the electrical part of this forum and I try to help DIYers with my understanding that they are not as knowledgeable as I am in electrical hence the reason why they ask questions and I try to work with them helping them understand better their issue and the resolution of it in more a friendly manner.


I only know enough HVAC to get into trouble! :O) One other possibility, and not sure why I didn't think of this before, would be to call Honeywell directly. I've had their tech and engineers guys on the phone a few times and they were always willing to help.
Thanks but I am not calling Honeywell or any other company. First reason is because my hearing is horrible on the phone and it is totally frustrating for me to talk to anyone on the phone. Second, this is not a big deal - I would like to have a digital thermostat or even a programmable one if possible but I am not jumping through hoops and going way out of my way to install one. If my system can handle a programmable one then fine, if not then fine. If it can only handle a digital one which will give me better control over the range of when the boiler kicks on and off so I don't freeze or die from the heat then fine.
 

kok328

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I forgot about battery operated thermostats, that will get you around the common wire issue.
Just make sure to keep up on the batteries or the boiler won't fire when needed.
 

afjes_2016

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ok, thanks kook328

Thanks for the video links Bud. I will check them out later today :thumb:
 

bud16415

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I forgot about battery operated thermostats, that will get you around the common wire issue.
Just make sure to keep up on the batteries or the boiler won't fire when needed.
Yep ours lasts over a year so we change them at the same time we change the smoke alarms each year. You can also have your smart phone or Alexa remind you.

Ours doesn't connect to the internet and I set up the time of day function and it wasn't bad when I was working but being retired I have it running pretty much like a dumb unit.
 

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