Gas furnace ignition system

James
James Solar Expert Posts: 250 ✭✭
Hello, the time has come to purchase a new LP gas furnace.
I'm wondering if anyone has experience or thoughts regarding the type of ignition system on a new furnace.

I do have grid power, but ocassionally lose power and i my solar system is used as a backup system for critical loads.

my current furnace is a standing pilot type, so not to much problem for the inverter to power the fan load. My concern is that most current ignition systems on the furnaces i've looked at are "hot surface ignition" (glow coil) type.

I'm guessing this type pulls a good load while energized.
Has anyone here looked into this and or measured this load?

I'm wondering if this should even be of concern to me while looking for a new furnace. I don't see any spark ignition type furnaces out there in my search as of yet...are spark ignition systems still made, and if so, would'nt they use less power than glow coils?

I should mention i don't ussually use my generator to get thru an outage...don't need to.
any thoughts?
thanks

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Gas furnace ignition system

    Yea, the glow bars can draw upwards of 300-500 watts. Some stay on while the burner is running--others turn off when the flame/gas is on.

    One issue with some spark ignition systems--They need the grounded neutral or they will not reliably detect the flame burning (my stove will randomly spark or not if the hot/neutral is swapped).

    You do save a lot of energy without the standing pilot... However, if you have a long flue run, then you can have problems with condensation (flue does not stay warm and dry).

    Also, with 80% efficient furnaces--a long flue run can condense a fair amount of water--and is actually illegal (at least in my location).

    I had to use a 95%+ furnace with PVC flue because of the long run (and to replace the 80% that was dripping water and damaging the metal flue).

    It may be difficult to find a furnace without glow bar ignition. Somebody said here (as I recall) that people (women?) did not like the spark sound in the furnace (actually, now I think about it--that was when discussing off-grid stoves/ovens).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Gas furnace ignition system

    Hot surface ignition is a very high am draw, albeit for a short duration. If all one has to do is turn turn thfurnace on it is not a big deal, but routine cycling on and off will be a big concern.

    Most hot surface ignitions are tough to by pass, as the controll board needs to "see" a certain current draw for a certain time before opening a gas valve.

    You might consider area heaters like Rinnais, as they have spark ignition, and very low power draws, and re very gas efficient. Is also believe that tan still get standing pilot furnaces, but they are hard to find as AFUs are very low.

    Tony
  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    Re: Gas furnace ignition system

    I did a test on my gas furnace. When it first comes on the globar uses 400 watts. After the furnace blower goes thru the surge which I can,t measur the furnace settled down to 700 watts running. That is a 59,000 BTU or therabouts from memory in a doublewide manufactured home. My brother just replaced the boiler in his hotwater baseboard system last year and his furnace has a pilot light. I thing the name of the furnace is well-mcclaine or something similar. :Dsolarvic:D
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: Gas furnace ignition system

    I installed a stander pilot flame boiler about two years ago.

    Used http://www.weil-mclain.com/en/

    Chose it because:
    1.Run off inverter, no electronics, a 24vac transformer for the gas valve.
    2.Chimmy would need to be re-linned to use a condensing type unit.
    3.Cost savings of unit and no work on chimmy was more than the gas savings if I went with a 98% AFUE unit.
  • James
    James Solar Expert Posts: 250 ✭✭
    Re: Gas furnace ignition system

    Hello and thanks for the replies.
    I determined that the furnace i'm considering does use a glow oil ignition and it only is energized during ignition and not during burner run time. Still not to good as far as i'm concerned. i would to find flame pilot system to reduce amp pull. 400-500 watts is not much for a short duration but the on'off cycles add up fast. i'm still looking for any standing pilot upflow furnace, 80% AFLU ok.
    ?????
  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    Re: Gas furnace ignition system

    n3Qik. That looks like the gas furnace My brother put in towards end of feb or early march. His old boiler was plugged up so bad it couldn,t keep his house heated. It ran continiously. He told me his electric bill went down about $30.00 Didn,t know a furnace could waste that much electric. :Dsolarvic:D
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: Gas furnace ignition system

    solarvic,

    My water ciculator pump, the smallest they come, will use about 1KWH/day. So, yep, they can use a lot electric.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Gas furnace ignition system
    n3qik wrote: »
    solarvic,

    My water circulator pump, the smallest they come, will use about 1KWH/day. So, yep, they can use a lot electric.

    how are you basing that ken as boilers don't run continuously with runtimes varying per outside/inside temps + heated area, insulation, and air tightness for agiven btu rated boiler? my crown has a standing pilot with about 80% efficiency and its pump has the markings of .71a and 115v. .71 x 115 = 81.65w. my electric has voltages around 125 to 126vac so this will bump my current and overall power consumption well over the stamped ratings and would be about 100w.
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: Gas furnace ignition system

    Had it wired to a Kill-A-Watt around Dec or Jan. Part of the energy audit I did that year.