Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How low is too low for return water temp.

ricking
ricking Member Posts: 34
Got cold enough lately for the boiler to run almost full time. Mid to low 20's and that is below normal. Radiant heat in ceiling with electric boiler. One zone. Did the refit on the boiler myself with excellent help from this site. All seems to be running fine. Just a little slower to heat house from 65 to 69 with colder temps. Supply temp is set at 115. The return water ranges from 80 to 85. Thats a nice spread but is it too low return temp. Not sure what the circulator is circulating in GPM but do those numbers sound ok?

Comments

  • hot_rod
    hot_rod Member Posts: 16,327
    does the boiler ever cycle off or does it run non stop?

    if the boiler cycles off, you probably have enough "horsepower" A load calc could help confirm that.

    Is it a multi speed circ pump? What speed? Kick it up if you can, lower ∆T will increase average surface temperature of the panel, and increase output.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • ricking
    ricking Member Posts: 34
    Pretty sure it does cycle off. It's a 3 stage boiler 34k per stage. Have'nt seen all 3 on. Maybe at start up to heat up the cool water. When water is up to temp on outlet, it runs mostly on 1st stage and that will turn off once and a while. One speed pump. There is no problem with the house not being warm. It is a very even heat through out the house. My thoughts were maybe if the return was higher, boiler would cycle off more saving costs. But. Heat transfer is heat transfer. Right? If it takes x number of BTU's to go up 1 degree.....
  • hot_rod
    hot_rod Member Posts: 16,327
    Ideally, the less a boiler, any mechanical component cycles the longer it will last and.

    in a perfect world heating equipment would cycle on and continuously modulate to the load, little if any cycling.

    If the home is comfortable, it sounds like you are good to go.

    BTU in vs BTU out

    Ceiling heat is not a ∆T sensitive as a floor panel would be. With floors 10- 15° is often a design ∆. As long as you are not walking on the ceiling, that surface temperature is not as critical.
    Cover the load with the lowest SWT, that is the goal of outdoor reset controls, and pursues best operating efficiency..
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,221
    Did I read correctly... 34kw per stage?
  • ricking
    ricking Member Posts: 34
    Sorry Harvey. Forgot the BTU after 34K. Its a 30kw boiler total. 6 -5k elements that stage 2 at a time. Total 102,360 btu.

    "As long as you are not walking on the ceiling, that surface temperature is not as critical."

    Those days are long over Bob. Thanks goodness.
  • Paul48
    Paul48 Member Posts: 4,469
    Do your neighbors lights dim when the boiler kicks on? Man.....My electric bill would kill me.
  • ratio
    ratio Member Posts: 3,185
    Oh, oh, oh—how 'bout an SCR on one stage? I'm pretty sure with a Honeywell T775 to control it you could get 99% turndown on that boiler!
  • Zman
    Zman Member Posts: 7,331
    In a perfect world it would be nice to get your delta t less than 20, just to even out the radiant temps. The bottom line is comfort.
    I agree with the outdoor reset recommendation.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordy
    Gordy Member Posts: 9,514
    The return temp for that boiler is fine.

    Do you use setbacks?
    Is this system zoned?
    Is the supply temp actually reading 112*?

    27 degree delta is pretty wide I think you would experience better comfort with a 15 delta. But if your happy that works then.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,221
    I have a feeling you will NEVER see it on the third stage. I might be tempted to disconnect one of the 5K elements from each stage, to give the boiler better temp control of the supply temp with less stress on your electrical system.
    Gordy