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Hot water heat piping layout advice

OhioRuss Member Posts: 29
edited February 2019 in Strictly Steam
I'm putting hot water heat in a 1870's house that has never had central heat. I've done heat loss and managed to source cast iron radiators, but I can't find anyone to do the piping so I'm going to have to. My instinct is to run 1/2" PAP to and from each radiator with a TRV, but I'm afraid the rads might interfere with each other. Is this a valid concern or is there a better way? I've attached a floor plan with heat loss and room dimensions. Thank you for any help. My wife is on me to close the ceilings below. Edit, this is for hot water, not steam. I don’t know how this ended up in strictly steam


  • Are you planning on using a manifold for supplies and returns?

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab
  • Gordy
    Gordy Member Posts: 9,537
    Home run rads to a manifold like @Alan (California Radiant) Forbes posted. Using a trv to control each rad.
  • OhioRuss
    OhioRuss Member Posts: 29
    Yes, a manifold was exactly what I was thinking. So I shouldn’t worry about having 5 thermostats (TRV) in an area of 1250sf?
  • It's not a problem, but you have to make allowances:

    1) Install a differential pressure bypass when only one radiator TRV is open to divert excess pump head.

    2) Near-boiler piping should be primary-secondary or install a buffer tank to prevent short-cycling.

    What kind of boiler do you have?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab
  • OhioRuss
    OhioRuss Member Posts: 29
    I haven’t gotten to purchasing a boiler yet. Right now I’m wanting to simply rough in the supply/return lines so I can enclose the ceilings. It sounds like I'll be okay with 1/2” PAP supply and return, and figure out that specific configuration once a get a boiler. I couldn’t find anyone to design a system for me; I only got one person even to talk seriously, and they would only swap out an old boiler. Thank you for all the help and I welcome any and all suggestions.
  • Where are you in Ohio?

    Don't we have any contractors there? If so, please tell Russ who you are.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab
  • OhioRuss
    OhioRuss Member Posts: 29
    I'm 30 minutes outside of Chillicothe; pretty remote. To be fair, this is a nasty job. None of the lines can be exposed and all the walls are brick. I'm an electrician by trade so I understand how miserable it is pulling up old floors and breaking open ceilings. The only person who would even come look said he only works with copper and won't install mod-cons - according to him they are incapable of heating cast iron rads. Maybe I’ll find someone to hook up the actual boiler once everything else is in place, but for now it's up to me. Again, thank you all so much.
  • pondman
    pondman Member Posts: 1
    My 1st post. Your project is interesting to me in that we just bought an old one floor & unfinished basement church rectory in the Eastern Townships of Quebec. The 1500 sq. ft house is heated with oil fired boiler to cast iron registers in basement & main floor. Electricity is much less expensive than heating oil. All piping is PAP and seems to function well except for the high cost of oil. Papers we found show $1,000/Winter month.
    The home has 400 Amp panel. I'm thinking of changing from boiler to tankless electric unit as a first step then gradually add or convert to heating zones. (basement separate thermostat etc.) I didn't find relevant info in the forums and would welcome ANY helpful inputs or comments.
  • Jamie Hall
    Jamie Hall Member Posts: 21,092
    @pondman -- might be better as independent thread, but... that said. I would be a little cautious about tankless hot water heaters for heating, although they have the virtue of being cheap. For a reason. Look up electric heating boilers and see if you can source one in your area, if one is the correct size. Not that a tankless won't work -- it will -- but the longevity may be poor. As a first step -- not bad.

    And in your area, with your subsidized electricity, it's probably the least expensive heat.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gerry gill
    gerry gill Member Posts: 3,058
    How reliable is the electric out there. For you people outside Ohio, we have an issue with this here. (sucks around me)
    If you go steam or gravity hot water you can make that boiler run off the grid if you want to chimney vent.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • OhioRuss
    OhioRuss Member Posts: 29
    I had originally considered an electric boiler, such as burnham used to make, but cost wise electric can’t compete in this area. However I did put in a 400 amp service in case circumstances change in the future. For now I’m planning to install a Lochinvar