Hot water furnace

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by pxp, Feb 2, 2007.

  1. pxp

    pxp New Member

    Feb 2, 2007
    I recently purchased a small condo in Virginia. The last two days have been cold and the furnace runs but it does not produce enough warm air. I checked the furnace and it looks different from the ones that I have seen before. This one has a hot water fed from the hot water tank. I am not sure how it works and I wonder if I need to raise the temperature of the water in the hot water tank in order to get warm air. Please advice.

  2. GoTanklessToday

    GoTanklessToday In the Trades

    Jan 11, 2007
    Renton, WA
    We call those "air handler" furnaces. There is likely a tempering valve on the outlet so that you can run the water heater higher than normal. Try turning the water heater up, but do so with caution, as the tempering valve may be out of whack. If it isn't workng to fix the problem, or if the tempering valve isn't adjusting properly to keep a safe temp at your taps, then call a professional.
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  4. perrycat

    perrycat New Member

    May 20, 2006
    Those are getting pretty common in N. Virginia, alot of condos have them I"ve seen. I'll tell you, there's a question I've had about those that nobody's ever been able to answer for me, how is it that those aren't a cross connection??
    They don't have a seperate coil for potable water, there's a tempering valve like you said so the water to the faucets is mixed with cold to make it 120 degrees or so. But going to the heat unit it's probably 160 or 180 degrees......AND...alot of them are piped in cpvc, which I always thought was amazing, I don't know what the threshold for hot water for cpvc is but that's pretty hot for plastic isnt it?.
    Anyway, as for getting more heat, try taking a hose and on the heating unit, there's a boiler drain, connect the hose and run it off the balcony don't water the plants of your downstairs neighbor, it's hot! And open up the valve and watch it. there should be some sputtering for a little bit like a minute or so and then a steady stream of water. What that does is flush out the air in the lines which can "air lock" some of the coils and the incoming water wont get up to those cause it's easier for it to just go where there's no opposition to the flow. So that will effectively reduce the available heat exchange area the unit has, causing the air blowing across it to be colder.
    Just think! all during the summer months, that same water is sitting in those pipes and that exchange unit, gathering god knows what kind of algae and stuff, then when you turn on the heat next fall, that goes into the water heater tank and mixes with the water you get our of your hot water faucets! Yummy!
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