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Backup water heater, which boiler and heating system.

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Beno, Dec 12, 2007.

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  1. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    I know electric is much slower recovery.Go for electric if thats what you want. I was just showing you a 92.7% efficient unit that would serve both DHW/backup heat, not take up much space and have no stanby loss. Your charts are also using rates from april 2004. probably figuring propane at 80% also.

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  2. Beno

    Beno New Member

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    The electric backup may not work, in order to get a building permit I need to prove that I have a conventional heating system in place, that means that the electric water heater should be able to provide alone enough hot water for covering the heat loss and DHW.
  3. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    If thats the case and still want electric you would need a electric boiler for your heat then use either and indirect tank or electric water heater for DHW.
    Using the electric water heater instead of the indirect for DHW would take up the same space and be much cheaper.

    This is probably one of the more wallet freindly electric boilers, It's pretty reliabe
    http://www.argoindustries.com/product_detail.asp?key=58
    If any one knows of others they can post them. I did argo Canada because thats where your building.
  4. Beno

    Beno New Member

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    I think that if there is no storage heat tank, I could use the indirect to supply DHW and connect the wood boiler to it and also connect the wood boiler to baseboards. Since the baseboards need a much higher temperature of the water than radiant in-floor, most of the heat will go to the indirect and baseboards, instead to the chimney. So, the question is, is this a good scenario if you don't have a storage heat tank?
  5. Nofossil

    Nofossil Moderator Emeritus

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    I dump heat into my indirect - in fact, I heat it way above the normal temp. I use a mixing valve (tempering valve?) to mix cooler water with it so that the DHW is correct at the tap. You can't store all that much heat in a DHW tank, though.

    I have a plumbing diagram on my site - link is below in my signature.
  6. Beno

    Beno New Member

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    What I understand from the diagram, nofossil, is that the indirect is just for the DHW, so any heat you dump there is used for the DHW only. You can't use the indirect to store heat to be used later for house heating, can you?
  7. Nofossil

    Nofossil Moderator Emeritus

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    You're correct. The DHW is essentially plumbed in parallel with my external storage tank. The DHW is just for DHW, while the external tank is used to heat the house, hot tub, and DHW as necessary.

    If I put a similar circulator on my DHW tank, then I could extract heat from it. At only 40 gallons, it wouldn't go very far. Also, cold DHW is a leading cause of domestic stress. Avoid it if possible.
  8. Beno

    Beno New Member

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    I am thinking here, for my utility room (8' x 19') I'll have to make room for: wood boiler, backup electric boiler for heating, large storage tank, indirect, backup electric water heater for DHW, plumbing, mechanical ventilation etc. It may be too tight.
  9. Nofossil

    Nofossil Moderator Emeritus

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    Same problem here. I ended up putting my storage tank outside for that reason. Also, no risk to the house in the event of failure.

    Some random thoughts:

    I'm liking electric hot water heater with sidearm heat exchanger and tempering valve as an alternative to having both indirect and electric tanks. If you have a backup electric boiler, that could also heat the indirect tank when needed, eliminating the need for the electric backup DHW heater.
  10. Beno

    Beno New Member

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    There is something I don't understand. The boiler (wood/electric/oil/etc) heats a closed loop of water, that heats the indirect through a HX. How can the same boiler heat the second loop that takes the hot water to the baseboards? You have one source of heat (the boiler) and 2 independent consumers: baseboards and DHW.
  11. Eric Johnson

    Eric Johnson Mod Emeritus

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    It's just two separate zones. One boiler; two loops; two pumps. The indirect is a separate zone. The zones branch off a manifold.

    I have two zones coming off my wood-fired boiler, one of which feeds hot water into my gas boiler, which has an additional 4 zones coming off of it.

    Is that what you're asking, Beno?

    Here's the returns for three of my zones to the gas boiler vessel. The pumps draw return water back down into the bottom of the boiler. They're activated by different room thermostats.

    Attached Files:

  12. Nofossil

    Nofossil Moderator Emeritus

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    Might be easier to think of it this way:

    The heat sources (oil boiler, wood boiler, storage tank) all are set up to draw water from a common cold 'return' manifold which is blue in my diagram. They heat this water and pump it out to the hot 'supply' manifold which is red in my diagram.

    Each heat consuming path or 'zone' has a valve which allows water to flow through it if there's a need for heat. That water flows from the hot supply manifold through the zone where heat is extracted and eventually to the cold return manifold.

    Any number of zone valves may be open at one time. If none are open, then there is no place for heat to go, and the heat source must shut down. There's a flow restrictor in the zone valves so that some water will go through each zone if multiple zones are open.

    There's not a single loop - there are many parallel paths.

    Hope this helps. Grab a friend with some plumbing experience, have a beer, and go over the plans.
  13. Beno

    Beno New Member

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    Yes, it's clear now. I can have one bolier and many zones, the indirect being one of them, and the manifold is distributing the heat among the zones. Thx
  14. Beno

    Beno New Member

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    Some more thoughts:
    1. Could I use the wood boiler just for the DHW (with the indirect), or it's too much just to heat 60 gal of hot water/day ?
    2. Could I use the wood boiler for the DHW and also with a water to air HX, and send the warm air through the air ducts, in parallel with the Caddy wood furnace? This way I use the whole house to store the heat, just like using a wood stove. Will this be an efficient way to transfer the heat from the wood boiler to the house? Will this work similar with the Caddy?
  15. Nofossil

    Nofossil Moderator Emeritus

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    Way more than you need to heat 60 gallons of water. Heating 60 gallons by 60 degrees uses less than 30,000 BTU. That's less than 1/2 hour output for the smallest of boilers.

    In the beginning of this thread, you were talking about radiant and/or baseboards. In my never-so-humble opinion, both are more desirable than hot air if you're using a boiler in the first place. You can do water-to-air, though.
  16. Beno

    Beno New Member

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    For now, I consider all the options, to be able to take at the end the right decision. Thanks for your help (and your patience).
  17. Bartman

    Bartman Member

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    Beno, please excuse the long winded story,
    It seems that I have a little bit of all the different options facing you here in my place. My home is a 3 bedroom ranch with attached 2 car garage, finished basement. When I built the house 22 yrs ago fuel was $1.20/gal when construction started, by the time I got my first oil delivery, it went down to $.39/gal. Some things never change. My heating system was originally going to be a solar assisted ground source heat pump, but that was over $10K back then. On my main floor I decided to just go with baseboard hot water heat. My dream was to have a finished basement, and my garage would never see a car parked in it. Both the garage and basement had to be heated, and that was going to be radiant. Nobody anywhere near me on Long Island had ever heard of anyone using radiant heat in the '80s, the last known radiant heat was in Levittown and that was a disaster, the originals had iron piping, the later designs were copper, both were nightmares. When I built my house no plumbing supply house here in NY had plastic tubing namely polybutylene, the stuff that class action suits are made of. At that time there were no lawsuits because problems didn't arise yet. Everywhere but NY polybutylene was legal for domestic water supply, so I had to have a 1000' roll of 1/2" poly airfreighted to me by my plumbing supply. The tubing is laid in the middle of my concrete which is 4" in the garage and basement, ty-raps hold the tubing to the 6x6x10ga wire reinforcement. This was the best thing I've ever done, it is the most comfortable heat in my house, and I don't use mixing or tempering valves, water runs through @160-180F. At that time there was no such thing as cross linked polyethylene tubing. If you are going slab, there's no other way. Although it take quite a while to get to temperature, once there it stays. My boiler combo has worked well for all those years without any major problems except for my steel boiler rotting out this year. And here's the kick, when my boiler was removed this summer I heated my DHW witha a small wall mounted point of use electric 115V water heater, it served as my boiler. My water heater is an indirect water heater, it's an Amtrol Boiler Mate Hot Water Maker, although not the most insulated, (it was 22 yrs ago), the new units surpass it temp loss ratings. With just my wife and me all of our hot water needs were met using this little water heater as my boiler. My hot water maker holds 41 gal, and the little electric "boiler" diligently made it's hot water at night and when we were at work. The unit is rated at 7 gal of HW an hour, but that's at 53 degrees F. When you're using it in a closed loop you're only losing maybe 20F in transfer. Some of my friends have garages with radiant heat in them and I used 30gal electric water heaters for heat, they work great. Radiant heat is slow transfer, especially in concrete, so electric water heaters can work albeit they run continuosly.

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