Does an indirect DHW tank really save you money?

Joseph_4

I was looking to put in an indirect hotwater tank. I priced it out. between the  SS pump, the new argo board for the boiler , the hot water tank, 1" copperlines.material is a fortune. Was told they are prone to leaking.is that true? was told over the long run a simple 50 gallon hot water tank will be more cost effective? what's your long term experience?

Thanks

Joe

Ironman

S.S. Pump

Why would you need a SS pump? And the piping could be done in pex-al-pex instead of copper.



 A good indirect is not prone to leaking. It should last 2 - 3 times what a gas water heater does. Also, it's much more efficient and the output would be about equal to the rating of the boiler.

Joseph_4

ss pump.

Your right I wrote ss b/c of booster tank setup. but was talking about indirect so scrap the ss pump.

Can you recommend a good indirect?

Thanks

 Joe

meplumber

any of the SS ones.

I personally like the Viessmann 100, but it can be pricey.  Almost all of the Stainless versions have a lifetime warranty.



The Triangle Tube/Weil McLain tanks are great for heat exchange as long as you don't live in an area where you have to drain (winterize) them every year.  I am in a highly seasonal area and they are a bear to winterize.

Ironman

Buderus Also...

Makes a long lasting tank by design, though it's not stainless.



TurboMax makes a reverse indirect that will give better output performance in a smaller package, but I don't know if the life expectancy would be that of a Viessmann or Buderus.



Another consideration: an indirect does not require an additional flue. A water heater would.

Joseph_4

Stainless steel indirects have a lifetime warranty?

I never knew anyone would offer a lifetime warranty on a tank.What they never leak?

thanks

Joe

Jean-David Beyer

Limited lifetime Warranty

My W-M indirect (Triangle Tube) warranty depends on whether it is used commercially or residentially. For residential use, it comes with a limited lifetime warranty. First year they will  replace anything if defect of material or workmanship. Second year and beyond, the will cover defect of material or workmanship of "tank assembly components." If a leak occurs, they will will replace the defective component. It does not cover labor or shipping. This is my paraphrase of the warranty, and I am not a lawyer.



I have had mine two years and it has not leaked. But that would probably be true of any tank.

meplumber

Very few SS tank failures.

The only failures that I have seen on the SS tanks has been at the welds where the nipples meet the tanks.  These seem to show up pretty quickly.  Usually in the first 6 months or so.  The manufacturers have been great about it. 



These are a rare occurrence.  As JDB stated, the warranties are all written by lawyers, so who knows what happens in 30 yrs when you try to claim.

Gordan

Turbomax longevity

The domestic circuit is copper in its entirety, and the tank contains boiler water. From the corrosion point of view, it should hold up very nicely as long as your boiler circuit is leak-free. My one point of concern is how the coil would hold up to mechanical stresses such as water hammer, since there's a lot of it and I've got doubts about how well it's supported.

Jells

I'm not very happy with my indirect

I installed one over the winter, and the standby losses appear to be substantial, from how much the boiler's cycling even when no water is being used. My office it in the basement and I can hear it.  I guess the standby losses from the old heater went up the vent, and were not as obvious as the hot climate around the boiler. I have not tried to compare gas bills yet however.



I have it running about 135 deg, and have done my best to insulate it, a fiberglass blanket around it, and polyfoam on the piping. I even have double heat trapping, both loops and nipples. If I could get it to hold it's heat, my WM CGi cold start boiler would take it easy all day. As it is, it's firing all day, and keeping all it's pipes, expansion tank and valve manifold hot and radiating. I'm regretting pitching the 10 year old conventional heater, I could have set it up for just summer use.



Of course, any ideas on what further I can do would be welcomed.

icesailor

SS Pumps Vs Bronze Pumps:

I think that you may see bronze pumps phased out because of lead issues. The Taco 006 pumps are priced the same as the bronze ones.

icesailor

Boiler running:

You have a wiring and/or control issue. The boiler should not run unless there is a call for heat which is the same as a call for hot water. If the tank stays hot all day and never calls for heat, you would never have the boiler fire. If it is running as you describe, you have a problem that needs to be resolved. If you have zone valves, one may not be closing properly and is keeping the TT circuit activated.

It should not be running if there is no call for hot water. The indirect is just another heating zone when set up properly.

Jean-David Beyer

I have one and it does not run as you describe.

I have a cold-start mod-con to drive my indirect. It is labeled Weil-McLain Ultra Plus and is presumably made by Triangle Tube. It is 36 gallons, and is of the tank-within-a-tank design with the domestic water in the inner tank.



There is only one person in the house, and I am not a teenage girl, so I do not use lots of hot water. My biggest hot water load is showering, with a 2 gallon per minute shower head. I also run a diswasher once or twice a week. I also run my washing machine about twice a week, but it runs either cold, or warm, so it does not use much hot water. I use about 12 therms a month to provide this hot water and any losses. The manufacturer suggests I lose about 1/2 degree per hour at an unspecifeid temperature difference to the environment. I do not have a recirculating system (though I wish i did). I have never sat in my garage (where the boiler is) and watched the boiler run in the summer, so I do not know exactly how often it runs, but my guess is that it runs two to three times a day. If I shower, get dressed, and rush out there, it sometimes runs, or has run recently (residual heat in the boiler, the pipes between boiler and indirect very warm). I am currently running mine at a little over 120F (though I intend to install a mixing valve and run it at 140F and mix it down to 120F).



The installation instructions say to have at least 12-inch heat traps in the supply and delivery in the domestic water pipes. I have closer to 5 feet because the supply comes in from the floor, and the delivery drops down to the slab where the hot water to the house is. I have 1/2 inch foam insulation on all these pipes, and on the drain pipe from the P/T valve part way to the floor (as far as I feel heat). This last may be a bit much, but I had some of the stuff left over, so why not. The hot water from the boiler is all insulated with 1/2 inch foam as well, and there is a spring-type check valve in the circulator in that circuit. The manufacturer calls for a flow check valve there, but the layout of the piping is such that there is about a four foot heat trap on the supply and a one-foot heat trap on the return, so that is enough.



I am not clear if you have both the domestic and the hot water line from the boiler heat trapped, or just the domestic. Do you have a flow-check in there in the line from the boiler? (or a zone valve where I have a circulator)? If not, your domestic may be keeping your boiler warm when it should be cold start. My boiler is not insulated, since it is cold start only, and the heat that leaks out serves only to pre-heat the combustion air, which is not much.



You should also check out your wiring as icesailor suggests. The only other possibility that comes to mind is if they forgot to insulate the indirect tank when they made it. I have not put any supplementary insulation on my tank, and it is not even slightly warm to the touch.

Jean-David Beyer

If you are afraid of water hammer, ...

... could you not put a water hammer arrestor at each end ot the coil (outside the tank, of course)?

Jells

There's no control problem

The tank is definitely calling for heat because it has cooled. I don't know if there's any way to increase the hysteresis of the thermostat.  The tank is on a zone valve, part of a manifold of valves coming from the circulator. It's a 10 year old Triangle tube 36 gal unit that I removed from another apartment where it was not an appropriate solution. The black foam under the vinyl jacket was rotting away, but I've put a standard blanket around it.



The boiler just kicked on, and no one has run hot water in 5 hrs.

Ironman

Have You...

Checked to see if you're leaking hot water somewhere? Leaky faucet? Hot water line that is concealed?



If you can isolate the domestic hot water line from the indirect and place a pressure gauge somewhere in it, that would show if you're leaking. You can get an adaptor that will allow you to connect the gauge to a hose bib, such as the hot one at your washer. Close the valve on the cold water side of the indirect and see if the pressure holds.

Jean-David Beyer

Revised gas usage.

My May-June and June-July gas bills were for 5.21 therms and 6.25 therms of gas. These months I am sure no heat was delivered for heating the house, so all of it was for hot water. The difference I attribute to variations in the amount of hot water I used each month.

Jean-David Beyer

If the black foam rotted, ...

... could there be a leak in the tank leaking to keep the foam wet? I do not think if it is dry that it would rot.

Jells

Leaking seems a very remote possibility

This is a 2 bath apartment, the 2nd floor bath is new, and I'd see a leak on my dining room ceiling, and if there were leaks in the ground floor bath or kitchen I'd see it in the basement.



As for the foam, it sounds like they don't use the same system anymore. There was no leak around the indirect.  The top and bottom of the assembly were white styrofoam, and fine, it was the softer black foam jacket that rotted.



I've seem many other types of soft foam rot. They simply dry oxidize. The only way to prevent it is nitrogen storage. The Muppets are made from several types of foam, including standard AC filter foam. They store them in nitrogen filled bags.

lchmb

circulating

Jells it sounds like your circulating around your domestic hot water loop and that is causing the tank to dump all it's heat. I found in one residence, a blending valve for a toilet was cross feeding. If you've got traps and your still feeding hot out to an expansion tank and all of your pipes are hot your water is moving some place. My indirect, if not used will go about 12 hours prior to a call to the boiler...

Jells

I don't have a loop

I assume you mean one of those "no wait for hot water " loops. Nope. This is plain vanilla plumbing, like I described. Tank right next to boiler, trap nipples & 1' loops. I do have a mixing valve, but that shouldn't allow much convection.  It seems the loss is mostly radiant from the copper pipes.



I'm wondering if there's a hysteresis setting in the tank's thermostat to adjust the gap between on and off, like on a Honeywell puck room thermostat. There's nothing about that in the manual. Since it appears the wires go directly to the thermocouple, can the thermocouple be replaced with one that'll have more range?

Robert_25

Differential

It sounds like your tank temperature control has a very small differential. My old 30 gallon WM indirect was the same way, if you rinsed the coffee pot out with hot water it would call for heat. My new indirect has a Honeywell L4006A aquastat with an adjustable differential.



Perhaps you could use a L4008A aquastat with a remote bulb in your WM.

Jells

Thanks Robert!

Now that's something to run down and sink my teeth into. I'm going to contact Triangle about replacements.

Robert_25

Report back

Let us know how you make out with Triangle T.