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Indirect or standard H.W. Heater

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Tony_8
Tony_8 Member Posts: 608
in THE MAIN WALL
I agree w/ your statement regarding exercise. I just don't like high mass boilers unless they need to be close to limit temp (190-200) most of the time. In a residence they seldom do. I have a lot of happy customers w/ indirects, and even more w/ low-mass boilers. There's a low-mass boiler for nearly every residential situation. You can easily achieve TRUE mid 80's eff w/ a low-mass on bbd and drop gas consumption compared to CI dry base boiler on same system. Done it, consistently.

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  • masterplumb
    masterplumb Member Posts: 93
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    Indirect or Standard HW Heater?

    I am replacing my boiler, and I was thinking of going indirect for my domestic h.w.. Now, my question to you guys is this, if I decide to install the indirect in my house, am I better off to keep the gas fired hw heater and use it in the warmer months when the boiler is not being used for heat, or is it more efficient to run the indirect year round? Thanks for your help guys. Chris
  • Dave_13
    Dave_13 Member Posts: 110
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    I am not an expert, nor is this my trade, but I would say to run the Indirect year around. Indirects are extremely well insulated and most are rated to only lose 1/2 degree an hour. A Hot Water Heater is no where near that and is only 55-60% efficient. Your boiler is probably a lot more efficient then that. From what I understand, your indirect tank efficiency is = to your boiler efficiency.
  • bill clinton_3
    bill clinton_3 Member Posts: 111
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    indirect

    The reason a water heater has such low efficiency ratings is that the ratings take into account the standby losses. If you have to fire up the boiler just to warm a tank of water through the indirect, you are going to throw away a lot of heat each time.

    I'm not completely sure it ever makes sense to use an indirect unless you've got that boiler already hot most of the year and you're not firing it up only to make hot water.

    Bill
  • Dave_13
    Dave_13 Member Posts: 110
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    ????

    Well that goes against all I've researched. It seems to me that if you have 85% heat going into water instead of 60%, your going to heat up the water alot faster. And if you have an 85% eff., 80,000 BTU boiler- it's going to run a lot less than a 60% eff., 40,000 BTU water heater. Am I wrong????
  • kf_2
    kf_2 Member Posts: 118
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    Indirect Heaters

    Bill,

    Suppose you had a post purge control on the indirect tank so that after the aquastat on the tank was satisfied the pump would still run for a short time to take the heat out of the boiler and put it into the well insulated tank. (these controls are available)

    This way, firing the boiler once in a while to make hot water is a lot better than firing a water heater alot.

    By looking at the published stand-by losses for an indirect as opposed to a direct fired heater you would be able to tell about how often each would call to make hot water.

    kf
  • Tony_8
    Tony_8 Member Posts: 608
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    efficiency

    of a std water heater is 80+ % when RUNNING. The posted eff. takes into account the standby loss of the neg draft of a vent removing heat constantly. A low mass boiler w/an indirect is faster and more eff year round than a std WH. I wouldn't want to fire up a cold cast iron boiler once a day for hot water.
  • masterplumb
    masterplumb Member Posts: 93
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    Heres my thinking

    If I have to heat the cast-iron boiler from a cold start which in turn heats the cold water in the indirect tank it would probably waste more energy then just heating the water from the standard h.w. heater, am i right? Chris
  • bill clinton_3
    bill clinton_3 Member Posts: 111
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    kf

    If, as Tony posts, you have a low mass boiler feeding the indirect, this probably works just fine and would be an energy saver. That low mass boiler would also have to work well with the rest of your system however.

    Even so, I don't much like indirects (excepting Buderus and Viessman). The finned coil inside will lime up if you give it half a chance, drastically reducing heat transfer and forcing that boiler to run hot all day and night.

    If you want absolute truth, I can only respond with a question: "Waddaya think I am, a philosopher?" (Stole that line from a carpenter :)
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    you'd

    be doing that boiler a favor by running it in summer-keeps it dry and keeps gaskets/seals set. Also keep in mind the longevity of an indirect vs. your typical water heater. Think about the extra maintenance/combustion air issues needed with two burners vs. one for a boiler/indirect.

    All things considered, an indirect makes sense. A tinny can with a fire underneath it does not. Glenn Stanton from Burnham had an excellent view on this subject a few months ago..Glenn..you out there?

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
  • Floyd_3
    Floyd_3 Member Posts: 32
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    I'll have some hard #'s soon.....

    Just fired up my new WM Ultra and switched from a standard HW heater to a Plus 40...

    I'm quite impressed so far... by the time I get out of the shower and get my fat a... whipped dry.....
    the sucker is purring along on low fire and a couple of minutes later is shutting down.

    I should just making hot water here SOON????? been so darn cool here that I'm still doin a little heating in the mornings yet!!!!!

    Maybe I'll have to wait for July's bill to get a good reading that I can compare...

    Oh well, when I get some #'s I'll be sure to share....
  • Dana Zaichkin_9
    Dana Zaichkin_9 Member Posts: 5
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    Combo units

    Like the Triangle Tube/Phase III direct fired units seem to have a place given this discussion - where I could imagine "system performance" exceeding higher efficiencies of other individual components. Tank-in-tank, a competent 85% burner, outer jacket water for space heating, insulation for the entire unit with the most common heat exchange directed inward. I have no direct experience with these, but am considering one. Any experiences?

    Best Regards

    DZ
  • Darin Cook_2
    Darin Cook_2 Member Posts: 205
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    Indirects

    I have installed many indirect water heaters(mostly Phase III and Buderus), they are a very efficient way of producing domestic hot water. Payback periods are normally around 3-5 years. Most of the tanks have a limited lifetime or 20 year warranty, you do not see any standard tank type direct fired heater with that warranty. Indirects have a very high ef rating (high 80's to low 90s) compared to a standard tank (mid 50's). That is not say you can not get high efficiency standard tanks with ef ratings in the mid 60's which are still good products, but the cost of those units are very close to the cost of an indirect.

    But no matter what type of tank address the water quality going through it. If you have extremely hard water and do not do anything about, expect problems. A indirect, especially a tank in tank design is much more resistant to those conditions. A direct fired tank which has the flame in direct contact with the steel of tank will much more rapidly pull the minerals out of suspension.

    We do alot of retrofit work through the NYS Energy Star program and have to provide a cost and savings report to the customer. Indirect water heaters always come out the most cost effective. You can always go to the orange box and pick out a buck fifty special and put it in cheap but you are not comparing apples to apples. If you are going to be in your home over 5 years then a indirect water heater should be your choice. Lots of information out there between the web and suppliers, do your homework and you will know the right choice to make. Good Luck!

  • HeavyP
    HeavyP Member Posts: 52
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    Heaters

    I guess the thing that I'm asking is if I do install the indirect, and keep the h.w heater, in the summer months, is it more efficient to use the hw heater instead of the indirect being that the boiler is not already making 180* water? In the winter months there is no doubt that I would use the indirect being that the boiler is already running. Thanks again . Chris
  • HeavyP
    HeavyP Member Posts: 52
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    Heaters

    I guess the thing that I'm asking is if I do install the indirect, and keep the h.w heater, in the summer months, is it more efficient to use the hw heater instead of the indirect being that the boiler is not already making 180* water? In the winter months there is no doubt that I would use the indirect being that the boiler is already running. Thanks again . Chris
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    Wish I could remember which website, but when researching indirects found something along this line from a MANUFACTURER...

    "...our indirects are intended to use the 'reserve power' of a boiler during periods of lower space heating demand. They will not be efficient when they are the only thing heated by the boiler..."

    No mention was made of type of system/boiler but presumed rather conventional.
  • Richard Miller_2
    Richard Miller_2 Member Posts: 139
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    indirect is more efficient

    It costs less to operate the boiler to heat your hot water than it does to use a stand alone water heater It should be clear you want to not use the stand alone at all.

    If it costs $100 to heat your water in a certain time period with a stand alone heater... And if an indirect costs $70 during the same time period... then who cares how much heat is wasted by firing up the boiler. It is still less than is wasted the other way. I think most on this thread are missing that obvious point. You have to look at the whole picture guys.

    Monthly gas bills will almost always drop when converting from stand alone to indirect even if you have a CI boiler. So who cares if the boiler wastes some heat? It is still LESS waste.
  • Darin Cook_2
    Darin Cook_2 Member Posts: 205
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    Indirect the way to go!!!!

    Chris,
    The answer is most definetly go with the indirect. Get rid of the direct fired tank. The boiler and indirect combo is greatly more efficient. It does not matter that the boiler is not sitting there at 180' plus during the summer. Your boiler will bring the water temp in the indirect tank very quickly. Your boiler will operate at much higher efficiencies than a standard tank ever could and due to the higher BTU input, recover much faster than the standard tank. Most indirect tanks have a standby loss of 1/2'F or less an hour. Compare that to a standard tank which continually vents all the dollars you just put on the water, right back up the chimney. Which is why the EF rating is low on a standard tank. Go with the indirect you will save yourself money. Plus you'll always be in hot water, wait that didn't sound right.
  • Jack_18
    Jack_18 Member Posts: 7
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    Indirect vs direct fired HWT

    Got in on this late, my wholesaler is proposing a Trinity boiler,(see new controls included), firing an indirect with a Conseco(?spelling) heat exchanger on return piping, to act as preheater for cold domestic entering entering indirect. This will keep boiler in condensing mode most of year. Any comments please?
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