Considering multi fuel furnace

Discussion in 'Homesteading Questions' started by Pouncer, Nov 16, 2006.

  1. Pouncer

    Pouncer Well-Known Member

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    Houston, we have a problem:

    Fuel consumption is through the roof, even tho this is a new home (less than two years old) and is 5 Star energy rated. The home is piped for gas, which we *could* hook up to (umpteen thousands, prices going up, a natural disaster means no heat after three days) The builder hired a heating and air contractor for the house. I now have a Delta Triangle system. It sucks. Here's how it works:

    Basically a 40 or 50 gallon well insulated hot water heater. Two "zones" on the unit-one supplies domestic hot water, one supplies heating. The heating line goes down into a sort of heat exchanger thing, where the hot water is circulated and a fan behind it blows it through the forced air ductwork. I also have the fancy schmancy air exchange system built into the house. This Delta Triangle has a one gal. per hour nozzle (no kidding) and in theory it should be relatively efficient to heat this home. It ain't.

    Last winter we tried hard to be conservative with the heating, yet still had plenty of months where we went through well over 200, 250 gallons of fuel a month. Talk about expensive! I have spoken to energy auditors, had a contractor come in and check the system (operating normally, btw) we stay on top of the air filters, etc etc.

    So to that end we added in Toyo stove. While you need electricity to operate them, it has surely improved the comfort of our main area by a lot! However, it can't help the rest of the house becuase it's a "split ranch" that is, rooms on either side of the main area. Those rooms can get pretty chilly as you can imagine, if we turn the heating system way down.

    Somehow we can't seem to get around the fuel consumption issue. I have been toying with the idea of going multi fuel (coal or wood, and oil, since these are abundant here) but cannot for the life of me figure out what is even a reasonably dependable make or model. I don't know anyone who owns one, and I don't know anyone who has added one to an existing home.

    I will be calling around next week to see what it make take (and what we could save) to switch over to a boiler with a boiler mate, and get rid of that huge oil gobbling hot water heater. If anyone can provide any info on multi-fuel I would love to hear about it!

    Thanks!
     
  2. MELOC

    MELOC Master Of My Domain

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  3. TheBlueOne

    TheBlueOne Well-Known Member

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  4. WisJim

    WisJim Well-Known Member Supporter

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    I would not go with a dual-fuel furnace as combustion chamber design and other factors differ between oil, gas, wood, and coal, and I feel it is better to have 2 furnaces if using 2 fuels, except coal and wood can be used in the same furnace.

    What part of the country are you in, and isn't the house insulated????
     
  5. MELOC

    MELOC Master Of My Domain

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    i think the furnace i linked may have a seperate chamber for the oil burner.
     
  6. agmantoo

    agmantoo agmantoo Supporter

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    I think you are adding problems with your consideration rather than fixing one. You live in a mild climate and have need for AC as well as affordable heat. Why not install a geothermal heat pump? Add some insulation and relax. Firing a multifuel system that is not efficient will only frustrate you farther IMO
    My error with determining your location, I saw the word Houston and made a bad association.
     
  7. Pouncer

    Pouncer Well-Known Member

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    Actually I am in Southcentral Alaska ;)

    I am pretty puzzled as to why our fuel consumption is easily 40% higher than the old house we had-which had 27 *old* windows, and was not very well insulated. I suspect there is some sort of fundemental flaw in the design somewhere. Today's chore is to see if I can find an energy auditor.........
     
  8. foxtrapper

    foxtrapper Well-Known Member Supporter

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    So you've got an oil fired hot water system. And it's got a hot water radiator in a box to transfer the heat to air, and the air is blown into the house. That's *not* efficient!

    Were it me, I'd be considering an oil furnace to use the ducting, or installing baseboard radiators to use the hot water. Either would be a heck of a lot better.

    And as long as you're considering things, consider one of the outdoor wood boilers/furnaces. They can be rigged both ways. They've come a long way in very recent years.

    PS A one gallon per hour oil burner nozzle should be quite sufficient to heat up to a moderate sized house.
     
  9. Ross

    Ross Moderator Staff Member Supporter

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    What you have is called a combo system and they are terrific, in mild climates, used in small houses/cottages. Even a mid range eff. oil furnace is going to cut your consumption alot. A boiler will do even better than that. I'd say now (without knowing how much hot water you're using) your heating system is running about 65-70% efficiient, a mid range will pull you up to 82ish, and a boiler will do 10% better than that and will give you your domestic hot water as well. A good boiler like Baisi or Newmac will get you there or if you really want to fix this thing right look at Veismann ($$). There are combination wood oil boilers, they're OK but if the wood firebox lasts 20 years that's only a half to a third the life of a cast oil fired boiler running alone. Get a good quality cast iron boiler, and a wood stove seperate. Your DWH/air handler is meant for much warmer states, where saving the cost of a furnace makes sence.
     
  10. Ross

    Ross Moderator Staff Member Supporter

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    Oh yeah balancing and sizing a Combo DWH/airhandler is extremely important, if it's not done correctly you can drop efficiency to less than 60%. I'd have to look up the ideal air temp rise and delta T for your water but I can't beleive they install these things in Alaska! They work here in E Ont, but it'd be a cottage.
     
  11. Pouncer

    Pouncer Well-Known Member

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    Ross, the blasted system is required for the five star energy rating-how stupid is that? I hate it. The builder doesn't have one in his own home, but he was told that it would handle the moisture from the bathrooms. It does NOT. Not even close. We are going to be adding an exhaust fan this coming summer.

    Honestly, most people I know who live in these houses are sick all the time with some sort of respatory something. These houses may be built tight, but they are NOT healthy either. I think the only reason we aren't is that all of us (including my son) are outdoors year round at least a couple times a day. As soon as the temps moderate, I open the windows and get fresh air in.

    I did call one energy auditor. Told her what was going on, and she says that's WAY too much consumption (194 gallons in just about exactly six weeks) given my location and the ambient temps. She was planning on researching the Delta Triangle and get back with me on Monday.

    The gold standard for boilers up here is the proven Weil McLain, although I know there are more efficent ones out there. I will do some checking on those brands you told me about, I don't recognize the name. One thing that bothered me was having basically only TWO zones on the darned thing....there should have been three: ONe for domestic, one for heating, and one for garage unit heater (which is also undersized)

    I personally think the nozzle is too big.
     
  12. Ross

    Ross Moderator Staff Member Supporter

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    Without knowing what size or brand of DWH is used I wouldn't speculate. There should be a rating decal on the front of the heater to size the nozzle. My 50 gallon Aero with an Aero burner uses a .65 gph so does my 3 gal John Woods DWH, but that hardly makes it gospel. Trying to over fire a burner above manufacturer specs to raise the recovery rate simply won't work, the combustion chamber won't be big enough to handle the added flame. So you'll get impingment and smoke, and wasted oil (smoke is unburned carbon from the oil). I imagine your choice for burner mechanics is limited? I'm not saying your water heater is over fired some may well be made to use 1 gph.
     
  13. Pouncer

    Pouncer Well-Known Member

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    No it's the correct size for the unit, I did have that checked. You can put on the smaller nozzle, without problems but I was told then it would not produce enough to meet the demands of the house.

    It has a Beckett unit built onto it, with Honeywell controls. Burner is Model # AF11 100, if that's any help. Temperature settings are in normal range too.
     
  14. Ross

    Ross Moderator Staff Member Supporter

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    Just supposing these units are working in other houses, meaning the house size and heat loss makes it a suitable unit then the problem is likely in the air handler. First thing to check is the condition of the coil, it has to be very clean, with air filters changed monthly or better. As i said before the set up and sizing is very important. Your water heater needs to have a high enough recovery ratign to keep the heat flowing, your air handler has to be large enough to bring up the nessicary air flow to say 90deg. f while not running a higher delta T of say 25deg f with 20 being more normal. The throttling valves need to be adjusted by someone who knows hydronic heating well and is using thermometers on the incoming and out going water and air! No small task and if anyone messes with the valves the system stops working. I am surprised to hear of it being used where you are, but ultimately you need to either replace it all or get it re-set up by someone there. If you get it re-set up, wire tie the throttling valve at it's setting! This would be one of the trickier DIY tasks.