(800) 853-2651
SHOP NOW

Hot water heating system thermostat puzzle

P

philcase

Member
I have a gas 3 zone hot water baseboard heat system in my home. The basement and 2nd floor systems work fine. I replaced the 1st floor zone control valve head because it would not close. Now it does not open and start the furnace every time the thermostat calls for heat. If I short out the thermostat connections with a jumpet wire at the valve until the valve opens and the furnace kicks on the zone valve will stay open and the furnace run until the temperature is reached. Once the valve opens and furnace is on I do not have to continue to hold the jumper wire on the terminals. Sometimes the furnace works when this thermostat calls for heat, sometimes not.
I am puzzled why I only have to short the terminals until the system starts and how to fix it. Honeywell t87f thermostat,
24 volts, mercury switch. Have I confused you enough?
Phil
 
Sounds like thermostat is not closeing the circuit when heat is called for. Maybe time for a new one, or is it one of those "smart" ones on a timer and the clock is out of sink with real time.
Loren
 
I have a 3-zone system also. Two years ago a huge power spike from a local booster station hit my electric panel and went through into the zoning equipment. After that it had similar symptoms as yours, the dampers would not work properly. Had to replace a circuit board.
 
My hot water system maintains boiler temp and only cycles when demand lowers boiler temp. The zone valves allow hot water to circulate through the system thus lowering the temp in the boiler causing it to cycle. If your hi and lo temp setting on the boiler are too close the boiler will fire almost Immediately after the thermostat calls for heat. Depending on the volume of heated water in the boiler the circulator starting may precede the boiler firing by several minutes. Modern gas and oil fired boilers hold much less water than the old cast iron boilers.
 
Yes it is an old thermostat. What I can not figure out is why when I bypass the thermostat until the valve is open I can leave it and it stays open until the thermostat opens. I am thinking some corrosion on contacts somewhere.
Phil
 
Sounds like the zone valve is miswired. Honeywell zone valve have four terminals: two for the motor and two for the switch. The motor should be in series with the thermostat for that particular zone and the 24 volt transformer, so the motor is energized whenever the thermostat switch closes. The switch is wired in parallel with the switches on the other zone valves and in series with the control box for the pump and boiler.

The way it's supposed to work is when the the thermostat closes, the zone valve motor opens the valve which also closes the switch in the zone valve. This in turn activates the boiler and pump. When the thermostat opens, the zone valve closes and the zone valve switch opens, shutting off the boiler and pump.

I think you have it wired in such a way that when the zone valve opens, the closed switch in the valve is keeping power applied to the zone valve, so once it's on it's stuck on. But the motor isn't getting powered normally by the thermostat, so it doesn't open when it's supposed to, only when you apply your jumper.
 
sounds like when the thermostat contacts close,another set of contacts close(holding circut)..
Is there a mirco switch at the zone valve?
 
I think the wiring is OK, just as you describe it. Sometimes it works fine but other times it does not activate the valve motor unless I jump the thermostat terminals on the valve. I only have to hold the jumper on long enough for the valve motor to open and contact the swich for the pump and burner. Tomorrow I will take the thermostat off the wall and check it out. If it doesn't start tonight I'll have to get up to pee anyway so I'll start it with the jumper then.
Phil
 
Sounds to me like the thermostat is not calling for heat. Have yoy checked the voltage at the zone valve when it malfunctions. If you have proper voltage the thermostat is good. May be the solennoid on the valve going bad. Just my thoughts.
 
The little motor that opens the valve is probably sticky. I have to replace one of the 4 in my house almost every year, sometimes even two of them. They are next to some hot water and thus run hot so the lubricant gets stiff. You don't have to replace the valve, just the motor assembly will do it. Watch so you don't lose that tiny screw when you take the old motor assembly off. If it falls to the floor you'll need a new screw because you won't be able to find it until you have bare feet and step on it.
 
RM-MN:
Dow-Corning makes a High-Temp Silicone Grease. If you can remove the lubricant in your motors and replace it with the High-Temp Grease it might just save you from having to replace the entire motor.

HTH

Doc
 
Even I am facing problem with my water heater,It takes very long time to warm water and consumes lot of electricity.One of my friend suggested me about Airdex waqter systems.So should I go with airdex or is there any option to do with my old one? http://www.airdexinc.com/about-airdex/service-area/
 
You must log in or register to reply here.

Similar threads

super99
Programmable thermostats
Replies
6
Views
706
MarkB_MI
MarkB_MI
T
Overheating (radiator/thermostat related)
Replies
18
Views
609
Bruce(OR)
B
L
Thermostat.
Replies
6
Views
656
Stan Coryell
S
G
1972 CAT D4D overheating
2 3 4
Replies
68
Views
2K
Cash4Toys
C
I
Oliver 550 Overheating
Replies
6
Views
637
hurleyjd
H
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top