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Recommendation regarding "smart" thermostatic valves for gravity hot water system

jahayman
jahayman Member Posts: 3
I have a gravity hot water system without a pump in our 2 story home in Michigan that was built around 1910. Almost 20 years ago now we had Honeywell T104B thermostatic valves installed on our 5 2nd story radiators. The controls on the valves never seemed to work well in terms of controlling the temperature in those rooms and so we rarely use them now. I am interested in installing a new set of electronically controlled valves. I came across the Honeywell Therapro HR90 valves which are electronic but they act independently and so I am wondering if anyone has a recommendation for wifi enabled thermostatic valves which could be controlled centrally and/or remotely and more accurately. Thanks in advance for any advice.

Comments

  • Derheatmeister
    Derheatmeister Member Posts: 1,524
    IMO...If your Gravity system conversion with to Honeywell T104B thermostatic valves did not work then upgrading to the Honeywell Therapro HR90 most likely will not make a difference.
    Piping changes may be required to make this work.
    Is your expansion tank/Vessel in the Attic or piped off the highest Radiator ?
    Some pictures of the system may help. :)
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,831
    edited April 2023
    How well could they work with gravity circulation? That's  Quite a Cv to overcome, no?  Mad Dog 
    DerheatmeisterGGross
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    What is the issue ? Too much ,too little or to control an Apartment ?
    I have enough experience to know , that I dont know it all
  • jahayman
    jahayman Member Posts: 3
    Sorry to be so slow to respond. Our expansion tank is an open tank in the attic and these valves are in the second floor of our house, not an apartment. The issue is that the thermostatic controller does not seem to regulate the temperature in the rooms at all. There is a table that comes as part of the installation instructions that says, for example, if you set the valve to 1 the temp in the room should go no higher than 61, if 3 no higher than 68, if 5 no higher than 75, etc. But whatever number I set it to the temp in the room as measured with a separate thermometer never gets above 60 in a 24 hour period whereas the other rooms are closer to 70. So really what I am looking for is a thermostatic valve controller that is electronic and will allow for greater control.
  • Jamie Hall
    Jamie Hall Member Posts: 23,162
    jahayman said:

    Sorry to be so slow to respond. Our expansion tank is an open tank in the attic and these valves are in the second floor of our house, not an apartment. The issue is that the thermostatic controller does not seem to regulate the temperature in the rooms at all. There is a table that comes as part of the installation instructions that says, for example, if you set the valve to 1 the temp in the room should go no higher than 61, if 3 no higher than 68, if 5 no higher than 75, etc. But whatever number I set it to the temp in the room as measured with a separate thermometer never gets above 60 in a 24 hour period whereas the other rooms are closer to 70. So really what I am looking for is a thermostatic valve controller that is electronic and will allow for greater control.

    The problem is as @Mad Dog_2 said that the resistance to flow from that valve, even when it is open, is too high (he used the technical term "CV" -- that's a measure of how much resistance the valve has to flow when it is open). Gravity flow heating systems are absurdly sensitive to flow resistance -- or to put it another way, water is very lazy, and will flow preferentially along the easiest path. In your situation, the easiest path for the water to follow is through the radiators which do NOT have any thermostatic valves on them -- which i take it would be your downstairs radiators.

    So -- bottom line is to remember that a valve cannot cause water to flow -- it can only restrict the flow. A thermostatic valve cannot warm a room up -- all it can do is make it cooler relative to other rooms which don't have restricting valves.

    Now. Problem. One might think that simply placing similar thermostatic valves on all the radiators in the house would be the answer -- but here we go back to the problem that the system is gravity flow. That means the only driving force for the water is the temperature difference -- and that is pretty weak. Odds are good that putting valves on all the radiators would make the entire system work poorly -- if at all

    So. New and different valves, however, magic they are they are with the electronics, aren't likely to help at all. You may have to convert the whole system to a pumped system to get the control you want out of it (you can keep the expansion tank arrangement you have; that's not a problem -- but the piping around the boiler will have to be rearranged and a circulating pump added, and some additional controls).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    HVACNUTMad Dog_2mattmia2
  • Tim_D
    Tim_D Member Posts: 128
    So you have TRV's on the second floor and standard radiator valves on the first floor? Where is the thermostat that cycles the burner, on the first floor? Do the risers to the second floor get warm? Do the bottoms of the second floor radiators get warm? Are your TRV's on the supply or return and if on the return did you check the supply side for orifice plates?
    Mad Dog_2
  • jahayman
    jahayman Member Posts: 3
    Tim:
    The thermostatic valves are on the 2nd floor radiators and are not on the 1st floor ones. The thermostat that controls the system is on the 1st floor. While I am not sure how to check the temperatures of the risers to the second floor the radiators on the second floor do get almost just as hot as those on the 1st floor and are hot on their tops and the bottoms (per an inexpensive infrared temperature detector but more so at the their tops than their bottoms which I assume is normal). As best I can tell the supplies come in on the left side of the radiators and the TRVs are on the left/supply side with one exception. As for orifice plates, I am not sure if they are there though I would hope that the plumber who installed the thermostatic valves 20 years ago would have taken them out.

    Jamie:
    Does the fact that the radiators on the 2nd floor with the TRVs are getting just as hot as the 1st floor ones when the thermostatic controller is not attached to their TRVs suggest that they are getting sufficient flow when the valve is open, that the flow through my gravity system is okay? If so, is the problem that when the controller is attached to the valve body the controller itself is creating too much resistance? That is why I am thinking a different type of controller might be needed. One thing that I did notice is that the one 2nd floor radiator with the TRV on the right/return side with the controller off was not hot like all the others and that the "pin" (not sure what it is called) was not fully up. So that one seemed to have the resistance issue you were talking about. But when I attach the controllers to the TRVs (with the ring screwed all the way down) there is too much resistance and hence I am wondering if I need new controllers which seems like will also require new TRVs.

    On a somewhat related note, are you aware of anyone in southeastern Michigan with expertise working on these systems?
  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,831
    Hmmm South East Michigan?  How far from Detroit Rock City?  Mad Dog 🐕 
  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,831
    Do Find A Contractor Search within 100 miles of you.  Keep walking the zipcodes till you hit the nearest Guy.  I think Steve Ebels was in Michigan?? Gerry Gill & Steve Pjajek
    Are Ohio or Wisconsin.  .somewhere out there.  Mad Dog 🐕 
  • GGross
    GGross Member Posts: 1,022
    @Mad Dog_2
    Ebels is more in the NW center of the state, but there would be no better choice for someone if they are within his service range.
  • PC7060
    PC7060 Member Posts: 1,155
    edited May 2023
    jahayman said:
    But when I attach the controllers to the TRVs (with the ring screwed all the way down) there is too much resistance and hence I am wondering if I need new controllers which seems like will also require new TRVs. On a somewhat related note, are you aware of anyone in southeastern Michigan with expertise working on these systems?
    It’s likely the control heads you have are not compatible with the valve. 

    I installed Honeywell TRVs in 2020 on my converted gravity system, all worked well under both gravity and pumped conditions. 
    Recently, I moved some radiators around and installed an older control head I picked up from a friend on one of the newer valve. I found that head would shut down the flow entirely, new model head worked fined. 

  • mattmia2
    mattmia2 Member Posts: 9,572
    So the room heats sufficiently or overheats when the control head is removed? It might be as @PC7060 said that the control head is wrong for the valve(or it needs an adapter or other hardware the installed did not install). With a radiator I would install a control head with a remote control or at least a remote sensing bulb that you can install a distance away from the radiator. If your control heads are just missing hardware I would try just getting the right hardware on one before replacing everything. Dig through the instructions and the catalog for the control head and the valve you have to make sure they are compatible.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    edited May 2023
    A simple solution would be to air bound the top floor radiators and bleed as you need to balance.....

    I have enough experience to know , that I dont know it all
  • leonz
    leonz Member Posts: 1,095
    jahayman said:

    I have a gravity hot water system without a pump in our 2 story home in Michigan that was built around 1910.

    Almost 20 years ago now we had Honeywell T104B thermostatic valves installed on our 5 2nd story radiators. The controls on the valves never seemed to work well in terms of controlling the temperature in those rooms and so we rarely use them now.

    I am interested in installing a new set of electronically controlled valves. I came across the Honeywell Therapro HR90 valves which are electronic but they act independently and so I am wondering if anyone has a recommendation for wifi enabled thermostatic valves which could be controlled centrally and/or remotely and more accurately. Thanks in advance for any advice.

    =================================================================
    Please don't waste your money on this. Gravity systems thrive on 3 things, vertical piping, the simplicity of the open water path and hot water.

    Adding controls other than a simple new replacement valve to shut water off to the specific radiator means you are trying to use electronic voodoo to make it work better and it won't.

    I would remove all those electronic valves, drain the system down and replace all the old valves and reinstall any missing orifice plates as you need the simplicity of orifice plates for your second floor radiators to slow down the water flow to these radiators to control the temperature.

    Simply closing the valves down a bit would control the hot water flow to these 5 radiators and it is a fits all method to do this if it is too hot on the second floor.


  • PC7060
    PC7060 Member Posts: 1,155
    edited May 2023
    leonz said:=
    Please don't waste your money on this. Gravity systems thrive on 3 things, vertical piping, the simplicity of the open water path and hot water. Adding controls other than a simple new replacement valve to shut water off to the specific radiator means you are trying to use electronic voodoo to make it work better and it won't. I would remove all those electronic valves, drain the system down and replace all the old valves and reinstall any missing orifice plates as you need the simplicity of orifice plates for your second floor radiators to slow down the water flow to these radiators to control the temperature. Simply closing the valves down a bit would control the hot water flow to these 5 radiators and it is a fits all method to do this if it is too hot on the second floor.
    @leonz - I think you recommendation would be good if the system was not already modified. The OP has already modified the system so there’s no reason that he shouldn’t try to fix the issue with the Mechnical TRV. 
    My personal experience is the TRV’s work exceptionally well and adapt to changing environmental conditions with no user intervention.  
    I agree with you entirely that the electronic units will provide no additional value. I’m not aware of an electronic TRV head approved for the US market. All the Honeywell ones I’ve seen are made for the European market and use European wireless frequencies and power
  • leonz
    leonz Member Posts: 1,095
    edited May 2023
    Speaking as a novice,

    For steam and pumped hot water they work well sure; but for a gravity hot water system that depends on the heat of 170-180 degree water to rise simply to the top of the piping and into the radiators along the way through the O-S fittings and back out through more O-S fittings if used to allow the cooler water to sink back to the basement to be heated again.

    What we do not know is whether this system is (1) an overhead hot water heating system which is the simplest, least troublesome and requires no bleeding or (2) a bottom fed system which requires air to be bled from each radiator or balanced with captive air in the top of each radiator or (3) if the orifice discs are still installed or (4) if O-S fittings are used.

    Pictures would be very helpful.

    PC7060