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Hydronic - pipe sizes mixed?

Just had a new gas furnace installed last year. Very old house, Maine weather... needless to say cold. I believe the term for the baseboard installed is "home run" or "single Loop". All on one zone currently is the cellar, 1st floor, and second floor. The thermostat is located about the center of the first floor area building foot print is 24' x 38' bungalow style. Currently standard 22 year old 3'4" piped hydronic base board heating units throughout. I have far to many questions as I move though this DIY upgrade of the home so I'll just go one at a time for now.
My living room / dining room is an open layout measuring 12' x 24' with tin ceiling and all. I wanted to keep a look of old and new for that combined area. The Pensotti Panel radiator seems to fit the "look" we want. Problem... or is it? I noted that the feed and return on the units is 1/2" piped. I've already planned to zone cellar, 1st, and 2nd floor independent but.. if I install a 1/2" Penscotti system do all of let's call it zone 2 (1st fl) have to be reworked to 1/2" feed/return also?


  • Jamie HallJamie Hall Posts: 10,548Member
    No -- I presume the rest is 3/4 inch? Just use a reducer near the radiator. So long as it's not a monoflo system, shouldn't make much difference.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • nativemaineahnativemaineah Posts: 5Member
    OK, so I'll come off the manifold reduce to 1/2" go through three of the Pensotti Panel radiator (about 24" of total radiator). Then I need to increase the pipe size 3/4" adapt back up to move through the remaining eight or so BB's (about 35' total) on the rest of the 1st floor. My concern is will the 1/2" lessen the BTU's on the remaining BB's?
  • Jamie HallJamie Hall Posts: 10,548Member
    No -- the half inch pipe won't by itself. However, the heat loss (temperature drop) through the radiators will, as will the slightly lower flow because you would have more head loss -- how much lower will depend on the pump characteristics.

    An alternative -- which may not be feasible -- would be to pipe the panel radiators in parallel with the baseboards. Then both would be getting the same input temperatures. Again, though, you should consider the characteristics of the pump -- and should probably have balancing valves on the two loops you have created.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • GordyGordy Posts: 9,264Member
    Are the pensotti rads replacing the baseboards, or an addition to them.

    If the fore mentioned, I would home run them to a manifold with o2 barrier pex in the boiler room, and then you could use trvs on the rads to control them individually. Pex is easy enough to run to the first floor if basement ceiling is open , but I don’t know the scenario for second floor..
  • nativemaineahnativemaineah Posts: 5Member
    First the replacement BB/Radiators - Pensotti is one I found online that looked like a interesting replacement. I also looked at Smith PSU-30 weighting the fan convector options. Myson's Lo-Line units are of interest too. Buderus model 21 & 22 seem to compare well with the Pensotti. Our bathroom is exceptionally cold so I'm going between an in floor unit or an in wall solution.
    On the subject of installation - talk about easy!
    Retired, no kids under feet and the wife is gone all day. Add to that sawsall, really big hammer, and a lot of time on my hands. Just recently removed all of the cellar ceiling drywall and replace knot & tube wiring (90% completed throughout building). Now working the 1st floor room by room the drywall is coming down completing wiring to each room new LED lighting, tray ceiling etc. A complete renovation!
    I'm approaching this in what might be considered a little strange. I want to install what works the best (heating appliances) based on the room. Bungalow story and a half with R19 throughout 1st floor ceilings.
    Panel or convectors seems to be the more efficient option for the largest living/dining room area (12' x 32). The one 1st fl bedroom 12'x12'currently has 14' of 20 yr. old fin BB. I have been looking at the Smith 8' HE2 Coil Block. The bathroom a recessed floor fan convector. The kitchen (10' x 12") a recessed wall fan convector and finally a "sun room" 12' x 15' slider door and lots of windows the PSU 40.
    As you can see it's quite a mix of diverse manufactures and approaches to heating this old house (112 yrs). About 50% of the building (waiting for warm weather to finish) has Polyisocyanurate Thermal Insulation Board (R24) installed and all of the windows have been upgraded to double pane gas filled.

    I understand I'll need multiple zones (how many still undetermined) to cover the entire house and am trying to build it out so I don't spend my final years scraping frost off my eyebrows (Maine - cold 6 months out of the year!).

  • GordyGordy Posts: 9,264Member
    edited February 10
    If you home run pipe your emitters you allow for control to each emitters temp by using a trv. Pipe them to a nice manifold with flow meters, and you can dial in flow rates, and even use actuators on the manifold for zoning as a different option.

    Trying to use the existing series piping ends up with flow issues, and the last emitter getting lower water temps. Using trvs this way while possible ends up getting a little more complicated as bypasses need to be installed so each emitter in series still gets flow.

    1/2” pex will carry 15k btus.
  • nativemaineahnativemaineah Posts: 5Member
    OK, just one quick question - what is a TRV? I'm going to work backwards and install all the system and have my gas tech do the final connect.
  • psb75psb75 Posts: 91Member
    Temperature Responsive Valve. Goes on inlet of radiator.
  • nativemaineahnativemaineah Posts: 5Member
  • clammyclammy Posts: 2,246Member
    Trv stands for thermostatic raditor valves . I would give a vote to buderus panel rads and a home run piping layout Use buderus trv on each rad and there by pass type isolation type raditor / pipe connection . I have the very system I used upinor pex aluminum pex tubing and a nice upionor manifold w flow indicators I top it off w a wilo ecm Stratos circ pump .i spent a little extra coin and sized them for low temp 140 max . If your using a cast iron boiler I would install a outdoor reset w return sensor to prevent flue condensation maybe even a taco I series valve fairly inexpensive in the mist of things I personally love them over baseboard and u can have trim don’t have to clean dust bunnies from under and they really blend into the room . Buderus has a manual on line that should help u out . Get a heat lose done on your home why spend extra on a boiler or panel rads a proper heat lose will help . One last note insulation and weather sealing is a good roi and a guaranteed on increased comfort and lower fuel comsumpition peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
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