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Noise issues- TACO X-block

PAXRodPAXRod Posts: 6Member
I just retro fitted my existing hot water and radiant heat system using a Sanden CO2 water heat pump and a TACO x-Block to control the radiant floor.
The only issue that I have is that the TACO block emits a vibrational sound that I find very irritating even though it does not bother my wife. We have a small house 1300 SF and I can hear the noise every where in the house. The original set up had some noise from the pumps but not as obnoxious as this noise. The original feed line piping was all 3/4 copper and I have isolated the Taco from the copper with sections of PEX. Thinking the noise was transmitted through the wall the unit is hung on I removed the Taco from it mounting. No change.
I am looking for possible solutions.
I am assuming that the pumps are okay as the x-block is new.
I have air bleeders on both sides of pumps
I do feed the hot to the X-block through a mixing valve
Our house is a little different than most in that the crawl space is a conditioned air space with no insulation in floor joist
Thanks for any thoughts


  • RichRich Posts: 2,477Member
    Could you show us a picture of this install ? Why is the X block being fed tempered water ?
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
  • Harvey RamerHarvey Ramer Posts: 2,115Member
    I would guess the mixing valve to be the culprit. It should not be needed with the X-block.
    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • PAXRodPAXRod Posts: 6Member
    Picture attached (i hope)
    The tempered water has to do with the Sanden CO2 heat pump. There are two parts to this system. An out side heat pump and an 83 gallon storage tank inside the house.The outside unit pulls water from the bottom of the tank and returns it to the top at 150F.
    When studying up on the Sanden system I was told by a number of sources that the return water from the TACO had to be kept low in temperature because it is returned to the bottom of the tank and if it is too warm it throws off the efficiency of the heat pump. When I looked at specs for the TACO XPB it talked about 20-30 degrees exchange rate. I assumed and maybe wrongly that this meant if my hot side to the XPB was at 150 then the return to tank would be 120 or higher which is too hot. By feeding the XPB 120F and connecting the return out of XPB to cold feed to mixing valve which is also cold feed to tank, I get my return to tank at less than 90- mostly 86 is what I read.
    I really like the Sanden system- For the two of us it heated our domestic hot water during summer months at rare of 1 KWH per day. Which by the way our solar panels easily met that small demand. It also took us off of using natural gas.

  • PAXRodPAXRod Posts: 6Member
    Harvey, You could be right- Next time it runs I will turn off the heat side pump and see if the noise stops.
    What temperature will the return to tank from XPB be if input temp is 150F and my floor feed temp is 85.
  • Harvey RamerHarvey Ramer Posts: 2,115Member
    If memory serves correctly, the x-block has a variable speed pump on the DHW side and a standard pump on the other side.

    What you want to do is this; pipe directly from the top of the water heater to the x-block and then back to the bottom of the heater. On the return line to the bottom of the heater, install a globe type balancing valve. Then turn on all your heating zones at the max temp that they will operate at. Using the x-block control, turn the variable speed pump to max rpm. Then using the globe valve, throttle back the flow till the desired water temp is met for the heating system. The return temp to the water heater will depend on the btu requirements of the heating system.

    If you have a center tapping on the water heater, that would be the ideal place to bring back the return from the x-block. If you have a spare tapping on the top, you could return it with a dip tube cut to the halfway mark of the heater.
    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • RichRich Posts: 2,477Member
    Where are you located and what type radiant floor install method are you utilizing ? In conversations with Sanden they cautioned about using this system for space heating applications .

    All may not be lost though depending on your answers
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
  • Joe MattielloJoe Mattiello Posts: 547Member
    Sorry to hear about the chatter resonating throughout the dwelling. However, this might be an easy fix. When the injection pump speed is reduced because of a light load, the velocity of the water is reduced also, and might not have enough to open check valve (IFC) all the way so it chatters. You can remove the check valve, and that should resolve the issue. Its probable redundant and not necessary anyway. Let me know how you make out.
    Joe Mattiello
    Application Field Service Engineer
    Taco, Inc.
  • Dave HDave H Posts: 303Member
    edited October 2017
    When you hear the noise, take a look at the controller and notice the number of "bars" displayed. These bars are an indication of the speed of the variable speed circulator.
    My guess at the moment may be that the numbers of bars seen are low since the demand for heat is also low at the moment.
    If you can adjust settings/parameters to make the circ speed up and the noise disappears then one of two options;

    As Harvey said, having a balancing (globe) valve will help. The low speed of the circ in conjunction with the internal check valve may cause some of the noise you hear.
    Or remove the check valve like Joe mentioned above if that is indeed where the noise is coming from

    Dave H.
    Dave H
  • PAXRodPAXRod Posts: 6Member
    Thanks for input every one -
    Harvey, you are correct about the Xpb having a variable speed pump on hot water side and a fixed on radiant floor side
    today while it was running I disconnected one of the pumps and then the other. There are two noises - one from each pump. The variable speed has a bit of a high pitch sound like a 60 cycle electrical whine. The constant speed pump which feeds the radiant floor makes the rumble that is driving me crazy. My conclusion at the moment is that the mixing valve is not the culprit causing the irritating noise and I do not see how it could cause the whine from the variable speed motor.
    I have something wrong in the radiant floor system - maybe something like water flow volumes.
    Harvey- I have a friend who works at WSU (Washigton state U) who studied these Sanden units - he is one that told me about issue with too hot return water and they did try a number of the things that you suggested - mid feed and the dip tube but not the globe type balancing valve ( I will study that some myself). For some reason they decided not to go that way. I think (at my age that is hard to do and some times is dangerous) that my mixing valve works for lowering return temps and it does not appear to be my noise problem.
    Re: system- located Olympia WA- not super cold here. House is about 1300 sqft, single floor. half of radiant heat is in a light weight concrete floor system- 1 1/2" concrete on platform framing and other half the tubes are under wood flooring. Crawl space is heated area with external walls ICF from footings to trusses. Walls are not the R value I was hoping for but attic is BIBs R50 insulation
    System is Wirsbo tubing and manifolds - one system with 8 loops in floor. I think it is easy to adjust water flow rate in each loop.Total floor tubing length is around 800' .
    Rich My friend that studied the Sanden had 8 houses that used both domestic water and heat. some had to set up back up heat but they are much bigger houses and in colder climates.
    Joe - it seems that the noise is on other side of XPB and from what you are saying then the lower my mixing valve is set the faster the variable speed motor will run. I put the check valve there because Taco showed one there in drawing and I thought it would stop thermo siphoning.
    Dave- I haven't noticed any bars but will look for them. I will play with the set up to increase that side circulation to see what happens.

    All- many thanks for your posts. As a retired small time residential contractor I have always been impressed with the skill and knowledge of the trades people and you guys exemplify my experience and feelings.
  • PAXRodPAXRod Posts: 6Member
    This is a little embarrassing -
    It turns out that the TACO XPB is tricky to purge- A good back purge- flowing water through XBlock in reverse direction to pump flow took care of the obnoxious growling noise. Air in pump - even though I had a good air separator in system and had done purging when setting up system.
    Thanks all
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 935Member
    Well that was easy! Glad to hear it's resolved, and a big thank you for posting your findings and not just leaving us wondering!
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
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