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  1. #1
    Join Date
    Feb 2014
    Location
    Pittsburgh, PA
    Posts
    6

    Jumping thermostat contacts

    I would like to install a programmable timer to control energizing one of my radiant zones that supplies radiant floor tubing in one of my bathrooms, which would replace an Uponor 2-wire radiant thermostat. The timer would close the circuit essentially placing a jumper across the thermostat contacts in my ZoneTrol II controller. The programmable timer would be independently powered.

    Questions:
    Is there any danger in placing a jumper across the thermostat contacts in the ZoneTrol? Does the control expect a certain level of resistance/impedance form the thermostat? Do I need to add any resistance to the circuit?

    I know that jumping the thermostat contacts will energize the zone and it will run without an issue in the short term. My concern is will it damage to the ZoneTrol controller over time.

    This is sort of a DIY question, but a small one that may require professional knowledge.

    Thanks,
    JK
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  2. #2
    Join Date
    Feb 2008
    Location
    Altmar, New York, United States
    Posts
    5,184
    why not a programmable tstat?

  3. #3
    Join Date
    Feb 2014
    Location
    Pittsburgh, PA
    Posts
    6
    Snupy

    The radiant floor tubing (zone 6) in the bathroom never generates sufficient heat to satisfy the radiant thermostat because of the size of the bathroom (BTU generatign capacity) and the placement of the thermostats (radiant and forced-air) in the adjacent bedroom. Both the bedroom and bathroom are heated by forced air on a single forced-air zone. This situation is fine as the radiant flooring provides comfortable floor warming while the forced-air heats the bedroom and bathroom. Also another bathroom in a separate part of the house is on this radiant zone. Currently, we turn the radiant t-stat up to warm the floor, just need some lead time.

    Also, perhaps more of a reason, I could not find a two wire programmable thermostat.

    The timer will be in the mechanical room in the basement.

    Thanks,
    JK

  4. #4
    Join Date
    Oct 2002
    Posts
    1,394
    Any programmable stat will work (battery powered). Use R and W connections

  5. #5
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    3,895
    a thermostat is just a dry switch anyway. when it calls for heat, the contacts close and your circuit is made. how is this any different than by placing a wire, wall switch, or temporary tstat across those terminals? (it's not any different).

    I could not find a two wire programmable thermostat
    All big box stores carry honeywell branded 2 wire programmable/non thermostats.
    Political Correctness, the language of wussies.

  6. #6
    Join Date
    Feb 2014
    Location
    Pittsburgh, PA
    Posts
    6
    Thanks for your responses.

    If I use a programmable t-stat, it would not function as a t-stat, but a timer. The “on” temperature will need to be set above the forced-air t-stat setting and below it for the “off” cycle. The two t-stats are next to each other.

    It appears the 2-sire t-stat steals power (draws current) from the circuit to run its components, but not enough power to energize the zone controller. So, I was concerned that the t-stat also controlled (limited) the current draw when the zone was energized, and that permitting the current to flow across a switch without any resistance may overload the controller. The ZoneTrol is a sophisticated device and who knows the requirements of the circuitry.

    Somewhat of an analogy; a 150W light bulb can be used in a light fixture rated for 75W. But, over time the socket and wiring will fail quicker and perhaps more catastrophically (wires catching fire) than normal. Short term use does not always guarantee long term use.

    If the t-stat contacts are a dry switch, then I am okay. I already have the timer and will go that route.

    Thanks again,
    JK

  7. #7
    Join Date
    Oct 2002
    Posts
    1,394
    As I stated, use battery powered stat, not power stealing

  8. #8
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    3,895
    using a power stealing stat is asking for problems.
    Political Correctness, the language of wussies.

  9. #9
    Join Date
    Feb 2014
    Location
    Pittsburgh, PA
    Posts
    6
    Thanks again for your replies.

    I failed to convey my true concern, which is will a switch without any resistance (jumper) damage the ZoneTrol controller. I do not really care about the t-stat other than to understand how it works. I already have a timer and will use it. So there is no need to buy a battery operated t-stat.

    Thanks,
    JK

  10. #10
    Join Date
    Aug 2002
    Location
    manitowoc wisconsin
    Posts
    4,943
    Why not close the forced air off for the bathroom for few days & leave the thermostat set up so the floor warms all the time?Infloor heat is a slow process it is by no means quick recovery.
    Do you wait till the timer comes on to take a pee in the middle of the night or just scoot across the cold floor?
    Turning down the thermostat,heating the room forced air,& now heat the floor with a timed on & no temperature control?
    You are a backwards mess IMO.
    Take your time & do it right!

  11. #11
    Join Date
    Feb 2014
    Location
    Pittsburgh, PA
    Posts
    6
    Markwolf

    Radiant heat has a slow recovery, but it is also has a slow dissipation. I plan to leverage the slow heat dissipation of the floor using the timer.

    These are two small bathrooms (~100 sqft total), and I only want to warm the floors with the radiant. This can be accomplished by cycling the radiant floor on-off every 2 hours, which I tested on some very cold days. Once the floor is warm, it takes more than 2 hours to completely dissipate the heat in the floor (i.e., the floor tile feels cold). Since the room is heated by forced air, the heat loss of the floor tile to the surrounding air is mitigated. Once the floor warms, there is a small difference (some times almost no difference) in the supply and return temperatures for this zone. So at that time the only expense is the circulating pump (zoned by pumps).

    The cost of running the zone on a 2-hour on-off cycle is probably small. The radiant is more about comfort than cost.

    My 80-year old mother-in-law occupies the one bedroom (the other is unoccupied). So I tell her to wear heavy socks to bed on the cold nights. Actually, on the colder days we run the zone constantly.

    My approach may add a small and perhaps unnecessary amount to the heating bill, but I think it is far from a backwards mess.

    Thanks,
    JK

  12. #12
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    3,895
    Quote Originally Posted by JK_Smith View Post
    Thanks again for your replies.

    I failed to convey my true concern, which is will a switch without any resistance (jumper) damage the ZoneTrol controller. I do not really care about the t-stat other than to understand how it works. I already have a timer and will use it. So there is no need to buy a battery operated t-stat.

    Thanks,
    JK
    a dead short is a dead short, whether activated by a relay in a tstat or by a jumper. no damage should occur.
    Political Correctness, the language of wussies.

  13. #13
    Join Date
    Aug 2002
    Location
    manitowoc wisconsin
    Posts
    4,943
    Quote Originally Posted by JK_Smith View Post
    Markwolf

    Radiant heat has a slow recovery, but it is also has a slow dissipation. I plan to leverage the slow heat dissipation of the floor using the timer.

    These are two small bathrooms (~100 sqft total), and I only want to warm the floors with the radiant. This can be accomplished by cycling the radiant floor on-off every 2 hours, which I tested on some very cold days. Once the floor is warm, it takes more than 2 hours to completely dissipate the heat in the floor (i.e., the floor tile feels cold). Since the room is heated by forced air, the heat loss of the floor tile to the surrounding air is mitigated. Once the floor warms, there is a small difference (some times almost no difference) in the supply and return temperatures for this zone. So at that time the only expense is the circulating pump (zoned by pumps).

    The cost of running the zone on a 2-hour on-off cycle is probably small. The radiant is more about comfort than cost.

    My 80-year old mother-in-law occupies the one bedroom (the other is unoccupied). So I tell her to wear heavy socks to bed on the cold nights. Actually, on the colder days we run the zone constantly.

    My approach may add a small and perhaps unnecessary amount to the heating bill, but I think it is far from a backwards mess.

    Thanks,
    JK
    A timer for heat control is backwards at best.
    A temperature sensor in the floor would keep the floor temp even without high & low spikes.
    The whole point of radiant floor heat is comfort not scalding or freezing your toes.

    - - - Updated - - -

    Quote Originally Posted by JK_Smith View Post
    Markwolf

    Radiant heat has a slow recovery, but it is also has a slow dissipation. I plan to leverage the slow heat dissipation of the floor using the timer.

    These are two small bathrooms (~100 sqft total), and I only want to warm the floors with the radiant. This can be accomplished by cycling the radiant floor on-off every 2 hours, which I tested on some very cold days. Once the floor is warm, it takes more than 2 hours to completely dissipate the heat in the floor (i.e., the floor tile feels cold). Since the room is heated by forced air, the heat loss of the floor tile to the surrounding air is mitigated. Once the floor warms, there is a small difference (some times almost no difference) in the supply and return temperatures for this zone. So at that time the only expense is the circulating pump (zoned by pumps).

    The cost of running the zone on a 2-hour on-off cycle is probably small. The radiant is more about comfort than cost.

    My 80-year old mother-in-law occupies the one bedroom (the other is unoccupied). So I tell her to wear heavy socks to bed on the cold nights. Actually, on the colder days we run the zone constantly.

    My approach may add a small and perhaps unnecessary amount to the heating bill, but I think it is far from a backwards mess.

    Thanks,
    JK
    A timer for heat control is backwards at best.
    A temperature sensor in the floor would keep the floor temp even without high & low spikes.
    The whole point of radiant floor heat is comfort not scalding or freezing your toes.
    Take your time & do it right!

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