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  1. #1

    Strange Thermostat/Controller Problem

    I am trying to solve a perplexing problem I think is with the thermostats and controller of my boiler system (hot water baseboard).

    I have a Peerless Purefire PF-80 with a Taco ZVC403-4 controller and two Hunter model 44110 programmable thermostats. We have two heating zones – upstairs and downstairs. The problem is, in the early morning when the first floor thermostat calls for heat, the furnace won’t come on. The yellow light on the controller turns on, indicating that the thermostat is communicating with the controller. In about thirty seconds, the red light on the controller comes on and the water valve opens. However, it is supposed to get the board’s main relay to close which activates the circulating pump and the furnace, but I don't think that happens (I don't think I heard the relay snap closed). Whenever the second floor thermostat calls for heat, it works perfectly. In addition, the furnace will stay on if the first floor thermostat is calling for heat after the second floor thermostat shuts off, but it seems that the second floor thermostat has to get things going.

    At this point we have replaced all batteries in the thermostats, we replaced the first floor thermostat and replaced the controller. When I rewire the thermostats at the controller so that they are operating the opposite zone, the upstairs thermostat continues to work properly with the system and the first floor thermostat continues to fail. (It does not seem that the circuitry of the controller is malfunctioning for the zone that was used for the first floor.) Thinking that there must be something wrong with the thermostat wire, I began tracing it out. I did find that they spliced it at one point and capped it with wire caps. They did not twist the wires together and they used too large a wire nut – only the tips were touching. I twisted the wires together and the first floor system worked – that one time. I think that there was some sparking while I was doing that and that may have jagged the system enough to get the controller main relay to close. It hasn’t really worked since, though.

    Has anyone else come across this sort of problem? Are these thermostats supposed to provide a certain amount of amperage to get the controller to do what it is supposed to do? The only thing I haven’t done yet is move the upstairs thermostat to the first floor to see if there’s something with the wiring I can’t see. It just seems that if it is communicating with the controller – turning on the yellow light and getting the water valve to open, it should be able to get the main relay to close. Thanks for any help with this! - Mike

  2. #2
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    was it working correctly before you replaced the t-stats?

    were the original t-stats the same model hunter?

    crystal ball on the fritz, that's all i can come up with
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  3. #3
    Hi dandyme -

    It has been in for three years and has generally worked well for the entire time. There were three or four times in that period, however, when we woke up and the entire house was cold - the furnace wasn't coming on for either thermostat. No fault messages. I just shut off the power to the system and turned it back on and it would kick on, as far as I remember.

    All of the thermostats - old and new - are the same model.

    I have read messages on other boards about the Taco controllers not fully responding to thermostats, but they weren't talking about my model. And, as I said above, if I wire the thermostats to different zones, the thermostat from upstairs will work. I would think that if there's a problem with the controller, it would consistently be in one zone. It also doesn't make sense that the controller would need to work on the current from the thermostat - I would think the thermostat would just trigger a relay and the board power would do the rest. But then, I could be wrong about all of this.

  4. #4
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,141
    You are correct... I would have the installing contractor check the relay contacts with each zone calling individually.
    ...

  5. #5
    Join Date
    Dec 2007
    Posts
    4,710
    does this unit also provide your domestic hot water, for sinks/showers?
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  6. #6
    @kangaroogod - the original installer changed businesses and does not respond to my calls. Getting someone else in will mean a large service fee just to come in - which I'm trying to avoid - especially since this is a convenience thing. The boiler works fine with a little fiddling.

    @pacnw - yes, it does supply domestic hot water, and we have not had any problems with that. It is controlled directly by the boiler and not the Taco controller. Having the domestic hot water turn on does not help the furnace respond to the first floor thermostat, as it does with the upstairs thermostat.

    Today, I went with a theorey that the main relay may be sticking. So, when the first floor thermostat called for heat and the furnace stayed on standby, I tapped on the relay. Nothing happened - no click, as I've heard when it works. I then walked over to were the wires were spliced and wiggled them. They were still twisted together, but I moved them enough to get them to rub together. The furnace and circulator kicked on. It could be just coincidence, but I'm beginning to think there's something with the wire. There's a lot of it I can't see because it's under ceiling tile in the basement. But, it still doesn't make sense that the signal/current from the thermostat is so important in making the controller completely function properly. I did finally go to the Taco site and sent them my scenario, as a homeowner with a residential heating problem - we'll see what happens.

    Thanks for all the thoughts!

  7. #7
    Join Date
    Feb 2013
    Location
    Ft Myers, FL
    Posts
    3
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary, or ask questions of the OP here.

    You can find the rules for posting and qualifications here.

    Further infractions may result in loss of posting privileges.
    Last edited by beenthere; 02-14-2013 at 05:13 PM. Reason: Non Pro * Member

  8. #8
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,013
    I realize you are trying to avoid paying someone else to come in and look at your system, but you've already (from what I've read) replaced the controller and poked around trying this and that to see if you can get it going. Did you buy a new Taco ZVC403-4? If you did and the problem still exists then that money was........ wasted.

    With your original contractor out of business sooner or later you are going to have to find someone to maintain your system. Maybe now is a good time to do so. Call around and ask questions looking for a company that specializes in hydronic heating and has technicians that know your kind of setup inside and out. Most technicians will gladly share with a homeowner how things work and answer your questions.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,125
    JLMULLIG, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here.

    You can find the rules for posting and qualifications here.

    Your post has been deleted.
    Further infractions may result in loss of posting privileges.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,141
    I'm sorry I cannot elaborate further as this is not a DIY site. As previously mentioned I would find the contractor that you are coin to be using for your annual maintenance now and have him come out for the routine service of the unit. It is a very easy to solve that problem in a failed condition with a meter and they very well take care of it Inexpensively to gain a new customer.
    ...

  11. #11
    Join Date
    Dec 2007
    Posts
    4,710
    as stated above, there is most likely a very simple(for TRAINED technician) fix to your problem.

    I can think of 2 right now with the info provided.

    either bite the bullet and pay for a PRO to look at you system, fix it and make any suggestion for other issues or just keep throwing money and time at it and MAYBE it will get fixed.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  12. #12
    I was able to contact someone at Taco. He thought that the water valve end switch (that tells the controller that the water valve is open) was probably failing. He suggested that I try jumpering the end switch at the controller, if I continued to see the first floor thermostat failing to get the system to work. I did jumper the #3 and #4 posts on the zone in question when the system failed, and that seems to have been the problem - its working now. Just thought I would post this, in case it's of some help to anyone else. Thanks for all of the suggestions!

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