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oil furnace, little to no hot water

Recently my wife and i I have noticed a significant change in hot water, mainly there does not seem to be much available. When hot water is available it's hot but it does not last. We have a furnace that heats out hot water and water for the baseboards (1 furnace) and I'm just not sure what it could be. Please help

Re: oil furnace, little to no hot water

sounds like you have a Boiler and not a furnace, Nashuatech will be along and give you all the info you need. Good Luck!!! :)

Re: oil furnace, little to no hot water


Yes, as Sten notes, from your description, you seem to have a BOILER that has a combo (combination) tankless coil for domestic water and boiler water for the baseboard.

The tankless coil consists of no more than a 15' copper coil inside the boiler that holds approx. a gallon or two of hot water for showers & tap water; as hot water is used for a shower, etc, the hot water inside the pipe is replaced by cold tap water from either the well or outside water supply; this incoming cold water has to be once again heated, which takes time, & you can end up with a cold shower---if there is hard water coming to the home from the water supply (usually a well), the internal coil is usually compromised over time with internal mineral depostis and its output is diminished.

Sometimes a city supply also has hard water with similar results---the only solution in such cases is to replace the coil (coil: $200 + $300 labor = approx. $500).

But first, check to see if there is a tempering valve on the HW line leading from the round, circular point at the front facing of the boiler up to the fixtures---sometimes these TV's get clogged & can strongly limit the flow of water---if you find a TV try to twist it back & forth at its adjustment knob to see if the flow improves.

Back in the old days, if the coil was clogged with minerals, some hot water heating techs would run some chemicals thru the coil to remove the calcium deposits, but few do that these days---they just replace the coil.

A more sensible solution if the coil is blocked with minerals, is to install a 30 gal or 40 gal indirect hot water heater storage tank, which assures almost unlimited domestic HW supply at often less cost than that being paid for the hassels with an inefficient coil---if the problem is minerals, the new coil will only clog up again.

An indirect HW heater circulates boiler water from the boiler & heats an inner tank for the domestic hot water supply (indirect HW heater: approx $700 + $300 labor = approx. $1k).

With your courrent coil, the boiler has to be kept at least 140 degrees at all times (using a triple aquastat) to keep the coil hot, as hw is needed at any time---this wastes a lot of fuel, especially in the summer months.

The tankless coil is suitable for a one-family household, but a first step perhaps should be to contact a local heating tech to get a quote as to how much they would charge for a replacement & also consider an indirect.

Hot water indirect heaters of 30 or 40 gallons are widely used with boilers, & they are highly efficient in making and storing hot water in their insulated tank system---strongly recommended, especially Triangle Tube Phase 3, Weil-McLain Gold Plus, TFI Everhot, or Lochinvar Squire.

Re: oil furnace, little to no hot water

Thanks for the advice. I did get a company to come out and clean the coil on my boiler and to my surprise it was quite clean on the inside. I wish the news had been different but I met witha few other vendors about it. I also consulted with a couple of friends who are engineers and agreed that the remedy was to install an indirect hot water heater. I selected the super stor ultra due to construction and very low heat loss. I am having the system installed friday 1/15 so I will comment about it's performance after that. I was a little discouraged with the pricing until I got a few quotes and realzed that in my area the costs are higher than estimated in this thread. My price for the purchase, installation, permits, taxes etc. is about $3K. Granted this is for a 45 gallon water heater but this seems to be the pricing in my area of new england. Thanks again for the great suggestions as it got me down the road towards having hot water again.

Re: oil furnace, little to no hot water

One nice thing about this purchase. Check out the Federal Government's green rules. You may be able to get a partial tax write-off if your furnace meets the government's criterias. It can be found online or you can have your contractor get it for you. A family member who is a contractor got a pamphlet but I don't know where from.

Re: oil furnace, little to no hot water

thanks for the info. I did a little checking and unfortunately was unable to find anything published aside from some things talking about green initiatives I did find that on energystar's webpage that the indirect water heaters do not qualify for a tax incentive (i.e. rebate) and I have posted the link and faq below for anyone interested. I will seeif there are any other incentives that I can take advantage of and will post them to this thread. Thanks again, Jon


Is there a tax credit for indirect water heaters?

Indirect water heaters are not mentioned in the tax credit law, so they are not eligible for a tax credit. The only water heaters eligible for a tax credit are electric heat pump water heaters, gas, propane, or oil water heaters, or solar water heaters.

Indirect water heaters use your furnace or boiler to heat the water in its storage tank. More on indirect-water heaters.


Section 25C(d)(3)(A) an electric heat pump water heater which yields an energy factor of at least 2.0 in the standard Department of Energy test procedure,

Section 25C(d)(3)(A)(D) a natural gas, propane, or oil water heater which has an energy factor of at least 0.82 or a thermal efficiency of at least 90 percent, and

Section 25D(1): The term "qualified solar water heating property expenditure" means an expenditure for property to heat water for use in a dwelling unit located in the United States and used as a residence by the taxpayer if at least half of the energy used by such property for such purpose is derived from the sun. Such term shall not include any facility with respect to which any qualified small wind energy property expenditure (as defined by subsection (d)(4) of section 25 D) is taken into account in determining the credit under such section.

Re: oil furnace, little to no hot water

Don't forget to check with your local State Energy Office in the state in which you live.

Check the white pages/blue pages of the phone book and online.

Most states have a rebate for energy star boilers and indirect heaters.

Also check with your local heating contractors (Yellow Pages: "Heating Contractors") for rebate items.

Re: oil furnace, little to no hot water

Is there some reason you didn't consider a tankless with propane?

This definitely would qualify for the 15% tax credit.

Does your state have energy efficiency rebates?

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