Replacing Zone Valve Taco 572-2 Motor Assembly and A Manual Override Question

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Old 01-20-16, 11:50 AM
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Replacing Zone Valve Taco 572-2 Motor Assembly and A Manual Override Question

I have a ranch house with a two zone oil heat system. House is built 1972, Utica boiler is from early nineties. One zone is to the front of the house where the living room, kitchen and family room is. The other zone is the bedrooms. When the front of the house heat stopped working late last winter, I thought it was the thermostat but the front of the house didn't get too cold, (it doesn't if the outside temp gets over 40 F in the afternoon), and the rear, (bedrooms), worked fine, so I didn't get around to doing anything.

I finally put in the thermostat and guess what, that isn't it. After doing some research, I checked around and found out out about zone valves. Also found out about replacing the motor assemblies without having to change the whole valve. I went downstairs and saw two Taco zone valves. One, Taco 571-2, is on a pipe which goes to the back of the house, (bedrooms), where the heat works. The other, Taco 572-2, is on a pipe going to the front of the house where the heat doesn't work. The Taco 572-2 is mounted on a larger pipe than the other.
[ATTACH=CONFIG]61856[/ATTACH]

Here is the link to a website with a picture and instructions.
http://s3.supplyhouse.com/product_fi...P-brochure.pdf
Also:
http://www.taco-hvac.com/uploads/Fil...ry/102-076.pdf This is for the new motor assembly.

I plan to put a new motor assembly on. However, it would be nice to get a little heat in the front of the house while I get the unit. My immediate question is, there is a lever on the side which is at the top of it's travel. It is set the AUTO at the top. On the bottom is the word OPEN. It appears to be a manual override. Can I put the lever down to the OPEN position to get some heat into the front? If so, do I need to disconnect anything electrical, or do I need to turn the electric off at the emergency switch or at the circuit breaker first?

I am a self taught electronic hobbyist, I design small amplifiers and signal generators, but I don't want to mess with this without taking asking questions first.

I appreciate any help I can get.
 
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  #2  
Old 01-20-16, 12:01 PM
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Yes, moving the lever to open should allow water to flow to the zone. Now that assumes the zone valve isn't working in auto and some other problem, like air lock, isn't preventing water to flow. But certainly try setting it to open and see if the heat comes on in that zone. You don't need to do anything electrical or turn anything off to do this.

If you set it to open and heat doesn't work in that zone...come back for more advice
 
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Old 01-20-16, 12:04 PM
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I should have mentioned that just setting valve to open won't turn on the circulator or fire the boiler, so you still need to set one of the thermostats high enough to start the circulator and fire the boiler.
 
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Old 01-20-16, 02:14 PM
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I set the thermostat at 75, went downstairs and pulled the lever down. It only went halfway down the groove. I don't believe in forcing things, so I left it that way for an hour and no heat came up in the problem zone. I was going to post here again like you said but that halfway position bothered me-why make a groove for a lever that it only travels halfway? Didn't make sense. So then I took some needlenose Vise-Grips and gently pulled the lever until it was almost all the way down to OPEN end. I went back upstairs and ran some hot water in the tub. After a couple of minutes, the heat came back on in the problem heating zone. Thank you.

By the way, when pulling the lever down to OPEN with the Vise-Grips, I accidentally brushed the pipe, which pushed the Vice-Grips to the side and the top housing started twisting off. I remember that the top housing was supposed to twist off when replacing the motor assembly, so I just twisted it back on and no harm seems to be done.

One more question. When the lever is in the OPEN zone, is it affected by the thermostat, or will the heat keep going regardless of where the thermostat is set?

If the answer is that the thermostat still controls the zone valve, even though it is in the OPEN position, what is the difference between the AUTO position and OPEN position?

I greatly appreciate your help so far.
 
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Old 01-20-16, 02:51 PM
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zone valve

When the zone valve is in the "open" position, it allows water to flow through that valve all the time. The circulator needs to be running to make the water flow, and the boiler has to fire to keep the water hot. This zone valve won't turn on the circulator or boiler, so the zone will only get hot when the other zone turns on the circulator and fires the boiler. I hope that makes sense-

Steve
 
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Old 01-20-16, 03:05 PM
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OK, good so far. You know that it is the zone valve that was preventing water flow in the zone.

What I suggest is that you move the lever back and forth a few times. Sometimes mineral build up in the valve causes it to stick and operating it manually a couple of time might free it. After moving it back and forth a few times you would return it to auto and see if it starts to work properly.

If it does, leave it auto and wash your hands, you're done. It might happen again but you'll know what to do. They are most likely to get stuck after sitting for a long time, like in summer.

If it doesn't begin working in auto mode, then ideally you would test to make sure the valve is getting electricity to rule out a wiring or control problem. If you have a multimeter, you would check for the presence of 24 VAC at terminals 1&2 of the valve when it is supposed to be open (thermostat calling for heat). If you have 24 volts but valve didn't open, problem is the valve, most likely the motor. If you don't have 24 volts, the problem is elsewhere.

If you don't have a multimeter, you can have someone move the thermostat up and down while you listen and feel for any indication the valve is trying to open. The Taco valves have thermal operators, so they don't make a lot of noise, but you may be able to feel some vibration.

To answer your question: with the lever in open position, that zone will get hot water any time either zone thermostat is calling for heat. It is no longer controlled by the thermostat.

Try moving the lever back and forth a few times and see if that frees up the valve.

Good luck!
 
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Old 01-20-16, 03:07 PM
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So in other words, the other zone's valve-the one in the AUTO position-essentially determines when heat can go on or not. If the other zone's thermostat is set low, the heat won't go on in the zone with the valve set to OPEN even if that zone's thermostat is set high. Basically, it becomes a one zone house, (which is not too bad for the short term)?

Is that right?
 
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Old 01-20-16, 03:23 PM
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Your post appeared while I was writing my other answer. I just went downstairs and moved the lever back and forth five times between AUTO and OPEN. It moves better now. I set it at AUTO and I'm going out now for awhile. I noticed on the way upstairs that the furnace stopped. This happened about a minute after I left the lever in AUTO. Regardless, I will see if the heat is off when I return in an hour or two. If the heat is off when I return, I will just do the steps you outlined-I have a multimeter. Much thanks for your help so far, at least I know I can get heat in the living room now. I do plan to replace the motor if it needs it, though.
 
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Old 01-21-16, 07:24 PM
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It takes a good amount of manual force to put the valve in manual overide mode, there is a 'heavy' spring in the valve body resisting the overide.

See how old the zone motor is, there is a date code on that slender over ride handle BTW. Those 'motors' are quite reliable, usually get a couple of 'decades' of use from them. It is gold colored right?
 
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Old 01-27-16, 09:43 AM
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Yes, it is gold colored. I bought a replacement motor-checked with the Taco company for the correct number. Turns out it is available in stock at both Lowe's, (where I bought it), and Home Depot.I am getting prepared to replace it. One thing-is there any reason I should NOT shut off the Emergency switch near the boiler and the circuit breaker that says "Furnace"?

It's replacement # 555-050RD

PS: I checked with the multimeter. In AUTO mode, the AC voltage between the # 1 wire and the #2 wire in the old unit is 24 Volts.
 
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Old 01-27-16, 10:57 AM
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Yes, you can turn them off while you work on it, no problem.
 
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Old 01-27-16, 11:43 AM
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Oops, while waiting for the answer I went ahead and did it. I turned off the power at the circuit breaker box which said "Furnace", but did not turn off the emergency power at the furnace. Just like I did when installing a new thermostat, which I probably didn't need to do, but it's cheaper than calling for service. Previously I had turned the thermostat down to 5F below room temperature. Things are working, but I have a question.

Now, one question. When I put the power back on and went up to the problem area upstairs and turned the thermostat up to 7F above room temperature, the heat in the baseboard radiator pipes took over five minutes to come on. I was expecting immediately. Is five minutes normal, or is immediately normal?

Also, I replaced the thermostat, Honeywell 87F, the original from 44 years ago, with a Honeywell CT87K, to preserve the look on the wall.
When I turned up the thermostat after the new zone valve motor had been connected from 5F below room temperature to 7 above room temperature, I detected a tiny click in the thermostat. Since the new thermostat is all electronic, is this normal also?
 
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Old 01-27-16, 06:57 PM
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When I put the power back on and went up to the problem area upstairs and turned the thermostat up to 7F above room temperature, the heat in the baseboard radiator pipes took over five minutes to come on. I was expecting immediately. Is five minutes normal, or is immediately normal?
I suspect your boiler is set up as a "cold start", in which case 5 minutes (plus or minus) would be normal.
 
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Old 01-27-16, 07:20 PM
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It would not be unusual for a thermostat to make a tiny click at the setpoint. They don't use the silent mercury switches anymore.
 
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Old 02-15-16, 10:53 AM
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Manual Override does not work

I have a 572-2 on my hot water heater that was working fine until yesterday. But yesterday, all of a sudden, nothing. I pushed the manual override to open, but still nothing. The furnace is working and the other zones (heating) are working fine. I'm not sure how to check if there is an airlock or if there might be another issue?

thanks for the help-,

Chris
 
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