Need Help Finding the Right Thermostat for my System [Smith Cast Iron (2 Wire)]

Philip_B

Hi All,

I am trying to figure out what the most functional thermostat is to get for my one pipe steam system. I do not care about having all the latest/greatest features like WIFI connectivity or anything like that - I just want to keep it simple, and have a thermostat that will allow my boiler to feed my radiators correctly and not constantly cycle on and off because its trying to maintain temperature within 1 or 2 degrees (I know that's not how the system is supposed to work).

System Information:

Boiler: Smith Cast Iron (Installed in 1994)

Number of Radiators: 8 (7/8 currently working, because I'm currently "restoring" the 8th unit)

Current Thermostat: RiteTemp 8029B (Simple two-wire/Battery Operated)

Size of house: Approximately 1600-1700 sq ft.

Background Information:

The Boiler and Thermostadt were installed by the previous owner. Overall the Boiler is in okay to good shape. I had the gas and heating components serviced by a professional 6 years ago (still working great), and I recently replaced the automatic water feeder myself after the old one stopped working.

I worked in the historic trades (Mason), so I'm smart enough to repair and "restore" things to a functional and well-kept state, but also smart enough know to when to hand things off to people that know what they are doing (gas/flame components, etc.). I'm also currently reading everything by Dan Holohan. That being said, replacing a thermostat and installing two wires doesn't' worry me. I just don't know what new thermostat will do what I am hoping it can do.

Outcome Desired

I want a simple thermostat that works with my current two wire setup, and allows me to delay it kicking on until temps in my house have dropped by roughly 5-6 degrees from the preferred temperature. In other words, if I want my house to be 68 degrees, I don't want the boiler kicking on until the thermostat reads 62 degrees. I don't want it coming on when its 67 degrees. This is why:

• From what I can tell, my boiler operates best when it has to raise the house temperature by 5 to 6 degrees. That takes approximately 25-30 minutes, and uses the majority of the water inside the boiler (but not all of it). Any more than 5-6 degrees and then the automatic water feeder kicks on for a second time, and the system has to reheat itself (which seems very wasteful for a few more degrees). Anything less than 5-6 degrees and then the boiler keeps kicking on and off, and it seems like the steam is more wet than dry. My assumption is because they system does not have enough time to drain back and air to clear the pipes.
• When I am home and can manually turn the boiler on and off, I use the above 5-6 degree drop as my gauge, and only have to turn it on 3 or 4 times throughout the whole day to keep the house comfortable but not excessively warm. I may be wrong, but that seems like pretty good efficiency to me.
• At night when I'm supposed to be sleeping or when I'm out of the house and can't manually turn the boiler on and off, the system is running almost every 15 to 30 minutes because of a one degree drop in temp. The whole system makes more noise, and seems to have to work harder for less gain.

Maybe that isn't perfect logic, but it makes sense to me. I appreciate any help you all can offer in advance.

Again, I'm not looking for the latest amazing thing, I just want better functionality than I have right now.

Best Regards,

P.

Eastman

@Philip_B

I would take pictures of the whole system. The experts on this forum are next level and can give you advice on small changes that could yield major results.

pecmsg

if only 2 wires

Find a T87 at a yard sale

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1876338#Comment_1876338

or Ebay

Philip_B

@Eastman - I plan on posting about other topics later. But I'm basically starting at ground zero. I've been scaling 1 of my 8 Radiators and got some new Hoffman vents (the real ones not the knock-off bluefins), replaced the water feed on the boiler, and have a full water glass replacement planned come spring time. Then its some black pipe repairs, fixing deteriorated pipe insulation, and having my friend who is an electrician help me clean up the chord management to the system and between the shut off and the feed. Basically bring the system from life support up to well kept (hopefully).

@pecmsg - I'm guessing you mean the T87F (with the mercury) that I've seen others mention? Are the non-mercury versions of the T87 no good or are they just not as good as the F? Anything is better then what I got right now.

So here is my question, what is the advantage to the T87? How does it help me make sure that my system isn't running for a 1 degree dip? Sorry if this explanation has been posted somewhere else, but I didn't see it.

@Jamie Hall - same questions as above to pecmsg.

And thank you all for your time, I appreciate it.

EBEBRATT-Ed

The new T87 digital thermostats are not reliable in my opinion. Look at Supply hous.com. Many models to choose from.

Ironman

You’re gonna have to get a higher end thermostat that would allow you to program the differential to 5 or 6*. Maybe a Honeywell T6 or above?

I’ve really never heard of someone wanting that and it’s sounds like you’ve got issues with the system that should be corrected instead of trying to operate it like that.

pecmsg

187K is a lot of boiler.

5°F swing is unheard of for heating.