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.

adding a 4-6' baseboard 'strip' ONTO existing hydronic loop

nroby Member Posts: 3
i recently bought a house with a 2 bedroom in-law apartment above the garage; as it turns out, the top floor bedroom does NOT have a baseboard heating 'strip' installed. The downstairs bedroom and living room and bathroom all do.

I'd like to add a 4-6' baseboard heating 'strip' to the upstairs bedroom. by 'strip' i mean a baseboard unit that runs hot water through it with heating fins etc, at one end 3/4" pex supply into the copper and at the other end copper back into 3/4" pex return.

my basic questions are:
> can i simply use Ts to tap into the bottom bedroom's supply and return lines to heat the upstairs bedroom with a heat strip?
> the rise to the second bedroom is about 12 - 14 ', straight up from the downstairs bedroom; will i need to do anything to compensate for the rise?

> should i install a zone valve and secondary thermostat for the heating strip in the 2nd bedroom to control the temp? ( i have one thermostat in the downstairs living room that controls the apartment loop)
> am i completely crazy?

ok no need to answer the last question, I've already come to the conclusion i'm not completely sane, but any advice or suggestions would be MUCH appreciated.


Nick from Maine


  • Ironman
    Ironman Member Posts: 7,375
    I'm somewhat crazy too, but I'm not hurting anyone so they leave me alone. It's the ones who mess with me that don't realize that I am crazy who are really in danger. :wink:

    You really haven't given enough info for a definitive answer, but here are a couple things:
    1. You don't want to just "Tee" into the supply and return of a single BB rad. You'll probably end up with issues in one or both of them and without being on site to see your complete system it's hard to say exactly what the best approach is.
    2. How do you know that 4-6 feet of baseboard will be sufficient? The only way to know for sure is to do an accurate heat loss calc as well as a survey of your present radiation. You'll not only need enough lineal feet of BB but it will also have to be sized proportionately to the rest of the system.
    3. The issue of controlling it would also require on site evaluation, but I'll caution you that you don't want to create a micro zone which would cause the boiler to short cycle. If you choose to do this modification, installing a TRV on the new rad while allowing the present thermostat to control the zone may be an option.
    4. You MUST use O2 barrier pex, not the regular plumbing pex that you find at your big box store or else you'll have a premature failure of your boiler, pump, piping, etc.

    If you'll post some pics of your boiler, it's near piping, some of your system piping and controls, we may be able to be more definitive.

    You may also want to consider just adding an electric BB heater. It probably won't cost that much to operate if the room isn't very large and it's well insulated.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • nroby
    nroby Member Posts: 3
    holy smokes that was fast, thank you so much for the advice, i will post pictures of the existing setup and near the boiler, etc when i get home tonight; hopefully that will be more helpful

    In answer to your questions, I *don't* definitively know that 4-6' of baseboard heat would be sufficient to heat this one room, however I'm basing my opinion on what I've seen in my house so far; i'm comparing this unheated room to a similar size room in the main house and contemplating using the same size base board strip.

    while not on site, what would be an alternative to a T from an existing supply and return loop? seems excessive to run a whole new loop from the boiler to heat that one room? but then again what do i know! :smile:

    and also is a TRV the same as a 'zone valve'? could i set it up on a thermostat for just that one strip, and not have to tie it into the switching relay at the boiler? as far as I know right now, i don't have any zone valves, but just circ. pumps that are connected to the switching relay (Taco SR506-4)

    now that you say it, i do believe that 'barrier pex' is what is being used throughout the house, for the heating and for DHW as well, not positive though
  • Ironman
    Ironman Member Posts: 7,375
    You MAY be able to pipe it in series from the return coming out of another rad if you size the new BB properly. Don't use the supply since that would rob btu's from that rad. So could using the return if there are other rads in series downstream.

    TRV = thermostatic radiator valve. It's non-electric an controls the flow into the rad from room temp. You cannot do this if the rad is piped in series, unless there's a bypass, as it would shut off all the rads in that series. It could not initiate a heat call, but could limit the room temp when the zone thermostat calls.

    Mono flow Tees MAY be an option, but let's see what you've got first.

    As you can see, this can be a lot more complex than first perceived. That's why doing the electric may become more appealing.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • nroby
    nroby Member Posts: 3
    thanks again for the valuable information, and while it does seem much more complex than i'd first anticipated, i believe it will be a worthwhile upgrade. i meant to mention this in my first comment back, i've looked into electric BB heat and i'm thinking that since i've already got a hydronic system in place i'd rather modify that than add electric heat. Due to my location the electricity is expensive comparatively to other parts of the country and thus i'd like to limit its use for heat, that being said, it would probably be way easier and less time consuming to simply install electric baseboard heat. Perhaps when I get a solar setup in place :smiley: