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Old radiant system eliminating baseboard heaters in basement

Pippin Member Posts: 4
I have just recently bought a house from the mid 1970's with a fuel oil boiler and baseboard fin heaters.  The water pipes also run through a woodburner.  We moved in January and used the fuel oil boiler but it is to expensive to run so we are stock piling wood for the next winter we live in northern ohio.  There are three baseboard heaters in the basement that I would like to disconnect they all have a pipe going in one end and another going out the other end and than go to the next baseboard heater this is all done with copper piping.  The problem we have is that it is a one story house and the bedrooms in the one end of the house are always cooler than the rest of the house and the water goes through the basement heaters first before it hits the bedrooms so if I bypass them than they should be warmer.  There are two zones and I am looking into upgrading them eventually to these heaters:

<a href="http://www.hitechheat.com/dd-20quotx202020.html">http://www.hitechheat.com/dd-20quotx202020.html</a>

I would like to just remove the heaters from the circuit and connect the supply and return lines together where the heaters were.

Let me know your opinions on the heater I want to upgrade to and if what I am trying to do is correct or not?  I do not think there are any mixing valves, or outdoor resets either.

The house is 1700 sqft with a full basement.

Thanks Brad


  • SWEI
    SWEI Member Posts: 7,356
    edited June 2012
    start with a heat loss calc

    And see what you need in each of those rooms.  Do you really want no heat at all in the basement?  Then decide what kind of water temp you want to run for the system in the future (lower is better as far as efficiency goes, if you ever intend to run oil or gas in the future.)  Those "Pensotti" radiators and towel warmers look suspiciously like Myson BTW.

    Sounds like your baseboard may be in a single series loop.  Removing the basement rads will help the cold rooms if they're at the beginning of the loop, but you might want to split the loop or re-pipe as a manifold system when you upgrade.

    If you're serious about heating with wood, do yourself a favor and read this http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf

    You almost certainly want a storage tank and an ODR-driven mixing valve.
  • jumper
    jumper Member Posts: 2,139
    first do the easiest

    try covering those baseboards with blankets & see how you like it.

    I do like your idea of replacing baseboards with radiant panels but you can easily throttle baseboards by stuffing intake.
  • Pippin
    Pippin Member Posts: 4

    Thanks for the replies.  I just started reading about burning wood.  The wood burner is in the basement so it heats the basement by itself and the heaters are really not needed.  I currently have the water set at 140 F.  When I first moved in it was at 180 F.

    One question I have is what is the storage tank for?


  • SWEI
    SWEI Member Posts: 7,356
    edited June 2012
    thermal storage

    Thermal storage is important for a wood-burning hydronic system for two reasons:

    1) Wood boilers run best when they burn hot and fast.  If they do have a means of throttling output, it usually results in lower combustion efficiency, creosote, and increased air pollution.  Your heating system 'wants' different temperatures depending on load.  This is what outdoor reset does for you.  Combining these two dictates a storage tank and a mixing valve.

    2) Fueling a wood boiler is hard work.  When you load and burn as much as the boiler can hold, you minimize the amount of physical labor required to heat your house. 

    Size the storage tank for as high a temperature as is practical (usually this means 180-190F.)   By combining this with a radiation system which operates on as low a temperature as possible, the required tank will be as small as possible, since storage capacity equals gallons x (high limit temp - low limit temp.)  You'll save money and space on the tank this way.
  • Pippin
    Pippin Member Posts: 4
    Storage Tank

    Let me see if I understand this completely.  My wood burner does have a thermostat that adjusts the damper as the temperature rises.  If I have a thermal storage tank I would let the wood burner run really hot to heat the water and than let it go out and the hot water tank will keep the house warm until I start another fire.

    In doing this I will get the maximum heat out of the wood and the heat would last longer instead of having to keep the fire going and wasting wood that may not be needed at the time.

     When the thermostat up in the living room is not calling for heat the wood burner does heat the pipes up to about 190 think I may have seen it as hot as 200 one time by the wood burner itself.  When I loaded it for over night and set the thermostat on the wood burner low so it would last all night it more or less smothers all night long it does keep the house warm but I can only imagine how much creosote it creates in doing so.

    I got into reading that article about burning wood with the system and did not realize how much is to the whole system.  Not sure where to start first adding a thermal storage tank or upgrade to panel heaters?  I have a limited amount of money right now so I cannot do it all at once. 


  • SWEI
    SWEI Member Posts: 7,356
    You've got it

    You want enough storage that you can load the boiler all the way up with wood and then burn it as efficiently (read that hot) as possible and capture all of that heat in one pass.  Once you live with a system like this, you won't want to go back.

    As far as priorities, I'd see what the costs (think time, money, and disruption of your space and home life) and benefits were to each part of the project and then come up with a strategy. 

    Just guessing (and assuming the boiler is in good shape) I'd probably add thermal storage and an ORC-driven mixing valve first, since that will have a direct and immediate impact on comfort and start saving you time and money once it is done.  Changing the type and sizing of radiation along with a piping rework could be done in stages (depending on room-by-room needs and budget.)
  • CMadatMe
    CMadatMe Member Posts: 3,086

    That that basement board is causing the issue. My bet is on zoning and the thermostat placement. Remove the board and the issue will still be there.. Its a small house the temp drop if I were a betting man might be 10 -12 degrees between supply and return.

    This read might help you on the wood/hydronic intergration.

    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Pippin
    Pippin Member Posts: 4
    Where to buy

    I looked up the valve and think I figured out which one I need the VRG 140, 4 way valve but not sure what controller to use.  I also tried to google it and could not find anywhere to buy them, is there any websites that sell them? 

    For the storage tank sizing high limit which would be 190 minus low limit I assume would be 140 but not sure about the how to figure out the gallons?

    I really appreciate the help.


  • SWEI
    SWEI Member Posts: 7,356
    step by step

    First you need to do a heat loss on the structure.  Then you determine (based on the existing radiation) what temperature water is required at design temp in order to meet that load.  From that and a delta-T for the loop you get the number of gallons per minute that will be required to circulate in the secondary (radiation) loop.  This dictates the size of your mixing valve.

    Next, you look at the BTU output of your boiler when it is at full fire, and (more specifically) how many BTUs are in a full load of the wood you will be burning.

    Now multiply the difference between the maximum storage temperature and the minimum useful storage temperature at design conditions (say 5F higher than the loop temp you determined in the first step above) by 500 and divide the BTUs per load (second step above) by that number.  Example:  If your system temp at design load is 140F and the maximum tank temp is 190F, that gives you a delta-T of 45F for the tank.  If the boiler produces 4 million BTUs from a full load, you divide that by 45 and again by 500 to get 178 gallons of tankx capacity.  Add 10% or so for safety and you might be looking for a 195 gallon storage tank.  Here's where you see how important low temperature radiation becomes - if your system temp were 120 degrees, the tank requirement would shrink to 123 gallons (~135 with a bit of margin.)

    You might want to consider hiring a good contractor or consultant for this - it's fairly important to get it right.
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