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An informal area for conversations, humor and observations that aren't necessarily strictly radio related. No discussion of politics or religion. Ads are not permitted.
A few months ago someone gave me an old brass thermostat with a clock in it that was made by the Minneapolis Heat Regulator Co. that I am guessing was made in the 1920s. My house was built in the mid/late 1910s, so something like this would look great on the wall compared to a hunk of plastic, but my question is, can it be made to work again? The heat is circulated hot water heated by an oil fired boiler. No A/C.
I've been getting a little frustrated with the quality of the heat-only thermostats currently manufactured. Not only is the calibration horribly off, but I've had to replace two in the past two years (lasted an average of 1 winter each).
See no reason why not. Unit probably consisted of a bimetallic strip, possibly damped by a spring, relay, and of course a mercury switch, that might be hard to come by if it's bad. Short of an earthquake, or chattering of the relay these were pretty hard to destroy. Wiring to and from the furnace and connections might need looking after.
Modern replacements allow a reduction of heat during sleep periods, which can help some on heating bills, but get a good quality one. Might just pay a little more and buy one from utility company.
The Minneapolis heat regulator is also a set-back thermostat, just like the modern units. The clock, which is a really nice jewelled eight-day movement, turns the thermostat down by an adjustable amount, and then raises the heat again in the morning.
These are nice units, but they do have a two or three degree operational range. I use two in my existing house , and am installing another in the new place.
"Gentlemen, you have come sixty days too late. The Depression is over" Herbert Hoover, June 6, 1930
Wasn't the Minneapolis Heat Regulator company a forrunner to Minneapolis Honeywell?
I assume that clock is a spring wound clock? Or, is it somehow electric?
In any case, how do you know it even needs to be rebuilt? Have you tested it out yet to see if it works? It might work just fine as it is.
If it does work, it shouldn't be a problem at all to connect with your current heating system. The water is probably circulated via a circulating pump. If that is so, then this thermostat would do well running that pump if connected via a motor contactor relay near the pump.
If it is gravity hot water, it would need to start the boiler. Assuming that boiler is operated already by a single pole thermostat, this one should work just fine in place of the existing one. However, depending on what voltage and current the boiler uses in the control circuit, you might want to put a relay between said thermostat and the boiler.
Problem is that they're only rated up to 6mA. That means adding a small circuit consisting of a transistor, or SCR, and a relay, plus a few other components.
Keep and eye out for old style thermostats, or mercury switches, at your local swap meets.
Life is like a roll of toilet paper - The closer you get the end, the faster it goes - A.E. Neuman
Many older thermostats have a resistive device called an anticipator. This is a resistance strip, rheostat actually that is calibrated in the amount of ma. the thermostat relay draws. The purpose of the anticipator is to heat up a given amount within the housing of the thermostat and pre-maturely raise the temperature of the room measuring element. This action accounts for the thermal lag of the heating system turning on and the actual heat reaching the thermostat. The net result is to more closely control the room without wide swings in temperature.
A vintage replacement thermostat should have the anticipator and have a rating within range of the relay. If the heating system control circuitry has been changed so that an electronic thermostat that does not use 24 vac at certain current requirements then the vintage thermostat may well look nice but do a poor job at controlling the temperature. What could be done is that a separate loop with a 24 vac relay that has a coil current rating needed be inserted between the vintage thermostat and the contacts on the new relay control the burner. Sounds very messy but if it is set up correctly it will work just fine.
I have set-up dual auxiliary heating/cooling relays to deal with a high current motor starter on the A/C unit. Looks very awkward, because I used DC relays with bridge rectifiers. Yes, there is an anticipator for the A/C too. it is in the form of a resistor that is only off when the A/C is on, the resistor heats the bi-metal thermostat. just like the Heating rheostat does...
BTW Though I have had a great deal of training on electrical controls, my favourites are still pneumatic controls, but one does not see them in a small home environment.
GL
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
Mark D wrote:Wasn't the Minneapolis Heat Regulator company a forrunner to Minneapolis Honeywell?
I assume that clock is a spring wound clock? Or, is it somehow electric?
In any case, how do you know it even needs to be rebuilt? Have you tested it out yet to see if it works? It might work just fine as it is.
If it does work, it shouldn't be a problem at all to connect with your current heating system. The water is probably circulated via a circulating pump. If that is so, then this thermostat would do well running that pump if connected via a motor contactor relay near the pump.
If it is gravity hot water, it would need to start the boiler. Assuming that boiler is operated already by a single pole thermostat, this one should work just fine in place of the existing one. However, depending on what voltage and current the boiler uses in the control circuit, you might want to put a relay between said thermostat and the boiler.
Mark D.
The Minneapolis heat regulator Company was indeed one of the forerunners of Minneapolis-Honeywell. The clock is indeed spring-wound, it swings away and is wound and set from the rear. The clock movement used in these is a really nice quality eight-day jewelled movement. It should be serviced by a watch repairman. A thorough cleaning and regulation should cost about forty dollars.
In the 1920's, Honeywell was the largest manufacturer of jeweled lever eight-day clock movements in the world. IN 1932, they introduced their all-electric Telechron Chronotherm:
"Gentlemen, you have come sixty days too late. The Depression is over" Herbert Hoover, June 6, 1930
Chas wrote:Many older thermostats have a resistive device called an anticipator. This is a resistance strip, rheostat actually that is calibrated in the amount of ma. the thermostat relay draws. The purpose of the anticipator is to heat up a given amount within the housing of the thermostat and pre-maturely raise the temperature of the room measuring element. This action accounts for the thermal lag of the heating system turning on and the actual heat reaching the thermostat. The net result is to more closely control the room without wide swings in temperature.
A vintage replacement thermostat should have the anticipator and have a rating within range of the relay. If the heating system control circuitry has been changed so that an electronic thermostat that does not use 24 vac at certain current requirements then the vintage thermostat may well look nice but do a poor job at controlling the temperature. What could be done is that a separate loop with a 24 vac relay that has a coil current rating needed be inserted between the vintage thermostat and the contacts on the new relay control the burner. Sounds very messy but if it is set up correctly it will work just fine.
I have set-up dual auxiliary heating/cooling relays to deal with a high current motor starter on the A/C unit. Looks very awkward, because I used DC relays with bridge rectifiers. Yes, there is an anticipator for the A/C too. it is in the form of a resistor that is only off when the A/C is on, the resistor heats the bi-metal thermostat. just like the Heating rheostat does...
BTW Though I have had a great deal of training on electrical controls, my favourites are still pneumatic controls, but one does not see them in a small home environment.
GL
Chas
These units do not have a heat anticipator. Just a simple coiled bimetallic strip with a lever and three platinum contacts , common, (the lever), open hot and open cold. They were used with dry batteries, generally 6 volts, common bell ringing transformers of the period (10-12 VAC) and in commercial applications the modern 24VAC transformer. The contacts in this unit will reliably carry a half-amp, and will work on any voltage up to 24.
I don't believe that the heat anticipator feature was introduced until the 'thirties.
"Gentlemen, you have come sixty days too late. The Depression is over" Herbert Hoover, June 6, 1930
