Indirect V. Direct Gas Hot Water Heat - Jay

Jay

trying to figure out if an indirect (using heat from gas boiler) or direct gas hot water boiler is more effficient?

my understanding is the indirect system is slightly more costly, but more efficent.

is this true? this is for a metro New York City house. any resources you can point me to? studies? comparisons? Bob Villa's private line?

kevin

indirects rule...

Indirect(ex. Superstor, MegaStor,Stor-ex,Phase III,Amtrol, etc) will last longer give you more hot water and be more efficient than a gas fired water heater. They have less standby losses, heat up the chimney & no standing pilot. It will also allow your boiler to run more in the summer(this is a good thing)Thats my 2 cents I sure there will be more. Kevin C. Good luck..Check out the web sites for the above heaters for more info..

Paul Pollets

Try

a Viessmann VitoCell 300. It will last the lifetime of the building and typically save 30-50% of the energy costs of running a direct gas-fired appliance. They can be run off a steam boiler, as well as a HW boiler. The stainless steel construction is unmatched.
See: www.viessman-us.com



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Jon Harrod

Indirects

Most new direct-fired gas water heaters are 55-65% efficient overall, when standby losses are taken into account. You can get ratings at http://www.gamanet.org/consumer/consumer.htm. The "Energy Factor" is the overall efficiency, expressed as a decimal (e.g. 0.55=55% efficient).

The efficiency of an indirect water heater depends on the efficiency of the boiler that heats it. A rough approximation of indirect tank efficiency is boiler AFUE - 7%. With an 92% efficient Munchkin boiler, your water heating efficiency would be about 85%.

Indirects are inherently more efficient because they have lower standby losses. A direct-fired tank may be insulated on the outside but has a big air-to-water heat exchanger running up the middle which through which heat is lost when the burner isn't firing. An indirect tank has an internal water-to-water heat exchanger. Standby losses are minimized because water flows through the boiler side of the heat exchanger only when the tank thermostat calls for heat.

The energy savings from an indirect will repay the extra cost in maybe 3 to 5 years. Indirects have other advantages: one less combustion appliance in the house means less risk of carbon monoxide spillage (as sometimes happens with atmospherically vented direct-fired water heaters). Also, faster recovery means you can eliminate the problem of running out of hot water.

I don't recommend instantaneous water heaters like the Aquastar. They are less efficient (70-80%) than an indirect tank, produce lower flow rates, and cost more to install.

Jon Harrod

PS


PS. I'm not sure what Bob Vila recommends, but Steve Thomas has an indirect tank. He did a promotional video for the New York State "Home Performance with Energy Star" program, in which he got a whole-house energy upgrade for his house in Salem, Mass. In addition to insulation and air sealing, he installed a Viessman oil boiler with an indirect water heater. You can order the free video:

1-877-NYSMART

Brian (Tankless) Wood

Hi Jay, Are you glad you

brought your question here.

Now check at "Find a contractor" and get someone close by to install your indirect for you.

I'm not sure if I directed you here from PLBG.com or Bob Vila, but I'm glad you made it, I hope you are too.

Brian (tankless) in Swampland.

Mark Eatherton1

Boy...

I hope Brian from Swamp land doesn't read this. He's going to dispute some of your quotations :-)

I looked at a TurboMax today. In fact met Pierre.

Interesting concept. Hey Jean, give ME a call or drop me a line. ;-) (hope she reads this...)

ME

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Unknown

heating system help!

I Live in a 60 year old 3 bedroom house in Vermont and I am removing my forced hot air system and installing hot water baseboard. I have two floors with a total of approx. 100lf of baseboard. Right now I have a gas water heater. I have been going back and forth on what to put in for a boiler.Some people suggest me getting a boiler for the baseboard and for the domestic hot water get a boiler mate. Other people suggest for me to get a boiler (system 2000?)that has domestic hot water coming off from it (maybe store it into a storage tank). I think the second option is cheaper since the cost of the boilers are about the same but the boiler mate is about $1000. I don't really know what it the best way to go. I was told having the domestic hot water right off the boiler, the boiler will be turning off and on all the time. The cost of this will pay for the boiler mate in just a few years. I don't know what to get.
Goal: Getting a good heating system, as efficient as possible. The way the oil is going up I don't mind paying a little extra for a better system. I also want to make sure I do not run out of hot water.

What do you think I should get. I am going "nuts" here. The web doesn't have much information on this stuff, it must be "TOP SECRET"

Floyd

A couple of things here

First, when your talking gas, is it LP or Nat. If you have Nat. available then you could do either gas or oil. I'm not a big fan of LP. Next don't do a coil in the boiler, they are trouble and the hot water is limited.
Hooking up a boiler to your basebaord with an indirect fired hot water heater is the way to go, but needs to be done right!!! That will give you a very dependable, efficient system with tons of hot water!
Go to "Find a contractor" and get a hold of someone in your area to help get it done "right".

hr

Do you currently have a boiler

How efficient is it. I'm not convinced a new indirect on an old boiler is all that efficient. The heat sourse drives the efficiency not the indirect.

How much hot water are you trying to generate?
If you don't have a boiler already I would consider a condensing tank type water heater or a modulating instantanous (Rennai, etc) your demands are comprable to their output.
Crunch the numbers and see.

An indirect and boiler install, if none currently exist, will carry a big upfront cost compared to the other option I mentioned.
Depends on how long you plan on living there, energy costs, hot water useage, and upfront costs.

hot rod

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Dale

The answer all depends on

what you think a reasonable payback for your money is. I know that for big business types it's 1 year or less. Given the value of cash if it won't pay for intself in 1 year most oil refiners, auto plants ect won't do it. Govt. agencies seem to go out to 3 years, maybe 5. Most homeowners seem to think 7 is reasonable. In the current economy how important is cash to you? I guess it depends on just how much hot water you use. There's a reason so many standard gas water heaters are sold. If you do the math, look at energy guide labels and compare a standard design, no electronics or electricity type nat gas water heater to a ergomax or similiar system the payback will be found. I have an old 1970 water heater, gas clothes dryer 92% furnace AC which runs all summer and my TOTAL utility cost is $73 a month (Budget Billing) for all gas and electricity for a typical 3 bedroom 2 bath house in Wisconsin. What's the payback for me in fuel cost saving to go to an indirect fired water heater? When I've done the payback math for others who once a month need extra hot water I see the well insulated electric water heater downstream in series from the standard gas heater as the least cost and least true cost option. All depends on how you value money.

John

Some answers...

I currently have a LP gas hot water heater that is about 8 years old. It has a non-stop flame. Between hot water and cooking I use about $35.00/month. It is currently providing hot water for 3 people.(maybe a 40 gal. tank) Sometimes we do run out if not carefull. I plan on removing my old forced hot air system and putting in a boiler (peerless...maybe, hints..ok? efficient?) I already have approx. 100 lf of baseboard in.
Money...um...Cost will be a big thing considering the boiler will be going onto a credit card for atleast 8 months (next years tax money). I was thinking about just putting in the boiler for now and in a couple of years putting in something for my hot water. I just want to design my system for it now. It looks like it might be best if I stay with the gas water heater..maybe buy a new one. Does the new one have an elec. Igniter now? Thanks for all of your help! John

Dale

The cost of standard water heaters

is soon to go way up. The manufacturers will need to sell them with a burner that limits explosion potential if gasoline is spilled near them. You can still buy a straight pilot light water heater, or if you prefer a direct vent one with electronic ignition and a vent motor. The only saving in the power vent is less construction cost on a new house and little more floor space. If you want to know what's the low cost option in your area look and see what your major tract home build on spec developers choose. If you have a workable chimney the value choice on a replacement is a standard pilot light heater with good insulation.

Dale

The cost of standard water heaters

is soon to go way up. The manufacturers will need to sell them with a burner that limits explosion potential if gasoline is spilled near them. You can still buy a straight pilot light water heater, or if you prefer a direct vent one with electronic ignition and a vent motor. The only saving in the power vent is less construction cost on a new house and little more floor space. If you want to know what's the low cost option in your area look and see what your major tract home build on spec developers choose. If you have a workable chimney the value choice on a replacement is a standard pilot light heater with good insulation.