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What are the implications of reducing radiator count on a one pipe steam system

Lost_in_NH
Lost_in_NH Member Posts: 12
I am a homeowner living in NH in a 1933, 2800 s.f. house. We have a one pipe steam system. We are in the process of building a 500 s.f. one floor addition with a full basement. Our plan is to heat the addition (first floor and basement) with radiant heat, either from a side arm heat exchanger or a separate condensing propane boiler.



Our plumber/heating pro has been trying to convince us to get rid of the steam system and convert 100% to a high efficiency propane boiler. I'm skeptical...Anyway, he has successfully convinced us to pull out three radiators and go with radiant heat to replace two radiators (in bathrooms) and for the third he was going to convert the one pipe radiators to HW. Before we agreed I expressed concern to the plumber that pulling radiators off the system might create problems. He was aware of what problems might be had, however, he was confidant that the system would function fine without the three radiators. I caved, but am now wondering if we've made a mistake (hence this posting).



In total our house had 18 radiators. In addition to the three radiators referenced above, there is an additional radiator that we plan to remove as a result of our addition (based on it's location). Hence there will be 14 radiators left, according to our current plan.



Other facts:



1) Our boiler was installed in 2007. It is a Peerless ECT-05 boiler firing at a rate of 1.5 gph resulting in a Net IBR rating of slightly below 159,000 BTUs. If the boiler is fired up to its max of 2.5 gph the Net IBR rating would increase to 215,000 BTUs.

2) The original walls in our house has very little insulation. Any walls we've opened up have been well insulated. Our new addition will be very well insulated.

3) On average we use approximately 1,000 gallons of oil per year.

4) We have an electric hot water heater that we rent from the utility company.



My questions are:



1) How can we analyze whether or not we will have a problem resulting from our removal of radiators from the existing steam system?

2) Will having a side arm heat exchanger help or hurt the situation?

3) Would a separate high efficiency condensing boiler be a better choice?

4) Would anyone on this board recommend fully converting to a propane HW system? If so why?



I've been very confused by this entire situation. Any help is greatly appreciated...Thank you!

Comments

  • Snowmelt
    Snowmelt Member Posts: 1,267
    Short cycle

    It may short cycle, unless you put a circulator pump on the return and still you the btu's



    We would like to see a picture of the boiler piping.



    I would get rid of the electric water heater and put an indirect.
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,313
    Oversized

    Removing radiators effectively creates a bigger boiler to radiator ratio. A boiler that is to big for its radiators will cause all sorts of problems.

    Step number one is to figure out the EDR or radiator btu output of all the remaining radiators. Next step is to compare that to the boiler ratings.
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    Boiler photo +

    Snowmelt, here is a photo of the boiler. I'm aware that short cycling is one concern, I assume banging pipes might be another.



    Steam Doctor, I'll try to get the remaining radiator BTU output tomorrow to post on this thread. If you would be willing to walk me through the analysis I would really appreciate it. Thanks.
  • icesailor
    icesailor Member Posts: 7,265
    Bioiler size/Radiator size:

    You need to measure the radiators you have that will be left and measure the EDR of them. Your boiler, ECT 05 is rated to fired at three rates. It is under fired at the lowest rate. The minimum rate it should be fired at is 1.75 GPH. It can be fired at up to 2.50 GPH. Usually, if you fire that boiler below the lowest rated firing rate, it isn't efficient and runs cold.

    But the boiler needs to fire into the existing radiation to properly steam. You need to tell what the total EDR of the existing radiation.

    In my experience, radiant floors in bathrooms are difficult. There's not enough floor space to to install the floor tubing. The space under cabinets, showers and tubs isn't counted. You usually need supplemental heat 
  • icesailor
    icesailor Member Posts: 7,265
    Bioiler size/Radiator size:

    You need to measure the radiators you have that will be left and measure the EDR of them. Your boiler, ECT 05 is rated to fired at three rates. It is under fired at the lowest rate. The minimum rate it should be fired at is 1.75 GPH. It can be fired at up to 2.50 GPH. Usually, if you fire that boiler below the lowest rated firing rate, it isn't efficient and runs cold.

    But the boiler needs to fire into the existing radiation to properly steam. You need to tell what the total EDR of the existing radiation.

    In my experience, radiant floors in bathrooms are difficult. There's not enough floor space to to install the floor tubing. The space under cabinets, showers and tubs isn't counted. You usually need supplemental heat 
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    Minimum fired rate

    Icesailor, won't the minimum fired rate have to be increased if we add the side arm heat exchanger to heat all the new space with hydronic radiant or radiators? That is one of the big questions I have, how will that impact the systems as a whole? For certain if we were to heat the new space with steam our boiler would most likely work better. The heating requirement for the new space is approximately 22,000 BTU's.



    My layperson's logic is that we'll need to increase the firing rate such that the Net IBR would be close to 181,000 BTUs (159,000 plus 22,000). That would seem to be accomplished at a 2 gph firing rate and a Net IBR rating of 180,000 BTUs. Is my logic correct or do you really need to isolate the steam system and make certain it is fully utilizing the boiler efficiently on it's own?



    I'm hoping we are ok with the radiant in the bathroom too, although I've wondered...Our plumber assured us it would work perfectly fine, but I don't think he did much of an analysis. In one bathroom we have the radiant under our bathtub, which is cast iron, and we do not have a vanity, only a pedestal sink. In the other bathroom we have the radiant under a custom shower (mortar bed) and a likely a console type sink. We've also been able to well insulate the walls. Any thoughts about how it will work out with the cast iron tub, mortar bed shower and no vanities?
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    I posted my reply in the main thread...

    Icesailor, thanks for your post. Please read my reply in the main thread.
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    Photo is in the main thread

    Snowmelt, I posted the a photo of our boiler in the main thread. Please check it out and comment, if you have any input. Thanks.
  • Steamhead
    Steamhead Member Posts: 14,343
    This Plumber

    sounds like he's creating more work for you to pay him for, either because he hates steam, or just to make more money.



    Keep the steam in those rooms.



    Steam is also a great way to heat an addition. We've done a few this way and are working on a small one now. I'll post pics when it's done.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    EDR & BTU output of Radiators

    Before removing any radiators the aggregate EDR is 658 with a total BTU output of 158,000 BTUs. After removing radiators the total EDR would be in the range of 538 to 563 with a total BTU output range of 129,000 to 135,000. I've used a range rather than a specific number because ultimately it depends on which radiators we remove; we might reshuffle some.



    If we use a side arm heat exchanger would we have to factor that into the equation? If the heat exchanger is set up to produce 45,000 BTUs of hydronic heat wouldn't that mean we would, net net, increase the firing rate of the boiler? I would think we would have the boiler set to fire at 2 gph vs it's current rate of 1.75 gph, which may make it more efficient.



    What I have no clue about, however, is whether that creates other problems? Anybody want to enlighten me?



    Much thanks.
  • Lost_in_NH
    Lost_in_NH Member Posts: 12
    edited June 2014
    Heating the addition...

    Thanks for the post Steamhead. I just replied to your earlier post with EDR information that I put together today. I'd be curious about your input on what I've posted.



    We would consider steam in our new addition but there is very little (almost no) wall space. It is an open style kitchen with numerous doorways/passageways. Do you have any creative suggestions about different types of radiators? Would you ever consider putting steam heat under a sitting bench for a kitchen table (think built in kitchen banquette)? The radiator would have to be real low (maybe 14 inches) and I wonder how it would be sitting on top of a steam radiator. Maybe not so good...
  • Fred
    Fred Member Posts: 8,516
    Window benches

    I have a couple window benches in the living room that have radiators in them. The heat is not noticeable on the seat and it is gentle from the front grill. The inside top and back are lined with tin which helps reflect the heat out the front but putting a radiator in a banquette is certainly do-able. May have to be closer to 16 to 18 inches but that would be about normal seating height.
  • Jamie Hall
    Jamie Hall Member Posts: 15,411
    The place I care for

    has a long radiator made of two finned iron pipes under a big window seat -- the thing is 8 feet long, two pipes.  Approximate EDR 61.  It really works well.  The seat is at normal seating height and width.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • vaporvac
    vaporvac Member Posts: 1,520
    they work great

    These were common in older homes. I had one in my kitchen which I'm re-locating to my front hall. There's on for sale $20 at my local Building Value if you're in the midwest. It's may 69edr guestimating. Colleen
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
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