Indirects

Brad White_71

Thanks for the kind words... of course you must know what I do for a living...

:^)>

The 80M will work fine as you describe it with even a 45 gallon SuperStor indirect. The heat loss is less than the boiler output and with the domestic it is the best match available. (The 50T is too small we agree). I would go with the 45 gallon unit; your first draw will be 15 gallons higher for short extra cost.

There are others far more familiar with setting up Munchkins; You may start another thread on the heating-side issues (Vision controls for example).

I am just commenting on the sizing and combination with the indirects.

Mark_46

Best Munchkin match

Any suggestions as to which indirect water heater is best suited for the Munchkin 80M? I assume their own Superstore would be?

Supply House Rick

After a recent visit to:

Triangle Tube in Blackwood, NJ. We saws first hand that Weil MClain, Peerless Partner were made by Traingle Tube, that lumps those together. The Phase III by Triangle Tube might be your best value, price, warranty etc...

Rick

Brad White_69

Nothing against the others but

why not stick with the Super-Stor by the same manufacturer no less? Common warranty and I think they market it as a package.

All are good products; things to compare are surface area of the exchanger, recovery time with the same boiler input and first hour draw and standby losses/insulation total R value (like any heater of course).

Mark_46

Yup

Brad, I would have guessed that using the Superstor by HT makes sense and other brands are no better?

I learned today that I may have to address a water heater issue as a result of building code conflicts. I am now scrambling to look into water heaters as quickly as possible. I wasnt planning on this up until today!

My first concern is having enough capacity from the Munchkin. Is it correct that indirects have more capacity and higher efficiency than a conventional water heater? Secondly is system design and how it all weaves together with the heat side...when both call for heat. Want to be sure the whole shooting match is piped/laid out correctly. Thirdly is cost.

J.C.A._3

Mark,

Don't forget warranty and adjusted cost to own.(I've literally had water heaters fail 6/10/12 years and 1 day after install! Then the cycle repeats itself infinitly) You're definately going in the right direction by using an indirect. HTP has an excellent tank in the SSU units. Couple this with the proper control stradegy and/or their own offering to get the most from your choice. Thermostats set to make heat before the big water demands....early morning and early evening, are a way to go but priority and programming of their proprietary control is quite easy.

Size accordingly and go fourth. Chris

Brad White_70

Indirect Heaters and Capacity

Unless I were to take apart each brand and see for myself, Mark, I would take most of them as being equal by their ratings.

Some units like the Amtrol have (or had by my memory) a coiled articulated copper exchanger. SuperStor is cupro-nickel (CuNi) a much harder metal. Others have coils of stainless steel (usually 316L). Some are tanks within tanks. It all gets down to surface area and the conductivity of that surface. CuNi is more conductive than stainless and is very close to copper, one of the best conductors when clean and not oxidized. CuNi does not oxidize easily nor of course does stainless.

The tanks are often stainless, also 316L usually. The Amtrol was (again, IIRC), a plastic, HDPE of some sort, I could be wrong. Today I am not sure.

My point is, each manufacturer does what they do a certain way toward the same goal, heating and holding water under pressure efficiently.

Your Munchkin is a fixed entity but if I understood correctly, the 80M has the ability to boost to over 100 MBH when in domestic water heating mode.

When I say the Munchkin is a fixed entity, I mean no matter what heater you use, it has to be driven by a known heat source. A bigger heater hooked up to a given boiler will wring out the heat, sure, but at what rate compared to draw? How long can you wait to charge the tank? Can the boiler keep up with the demand?

It is for this reason that HT Products makes recommendations for match-ups. And do not forget controls and ease of hook-up.

To your first concern/question, yes, indirects tend to have more capacity than conventional heaters. A typical 40 gallon heater will have a burner of between 33 and 40,000 BTUH input. An indirect is defined by it's boiler. My own, a Monitor MZ and companion, takes 100% of the boiler (about 90,000 BTUH or over 2.5 times my old 40-gallon heater) and heats the tank in about 10-15 minutes. Then it goes back to heating the house before I know it. Never have a blip in house heat and no, you do not add capacity to power these.

Cost for benefit? I like my indirect. It was a choice. I had a choice of either method and this is what I chose. Cost was an issue, benefit long term? Nothing like it.

In the end you can use any number of indirects. Each has a rating based on a BTU input. That is all you have to go on.

Best,

Brad

Mark_46

Brad / Chris

Great info as always, thanks. So it seems an indirect is superior to a conventional water heater.

Another concern I have is that the Munchkin would be running a lot, year round in fact, to produce heat and hot water during the winter and hot water during the summer. Wear and tear factor? Most boilers get the summer off ).

Sorry, can you define MBH?

Are indirects better insulated than conventional water heaters?

As far as capacity, I would think that 35 gallons is 35 gallons regardless of the device, no? Difference between conventional and indirects is that one has, as you say, 35-40K BTU burner where an indirect is defined by its boiler which is usually a lot more. The indirect can only recover quicker, right? This is what the first draw and first hour ratings are related to? But this of course changes drastically when the boiler is needed for house heat at the same time, no?

Finally, when seetting boiler outlet temps, what is it optimizerd for, heating or DHW? I guess heating, right? knowing the Munchkin likes those lower output temps.

hr

My experience shows

in hard water conditions the tank within tank design, or the brands with smooth coils as opposed to fin coils, hold up best.

The finned coil HX tend to drop off, efficiency-wise rather quickly with calcium deposits.

Of course treating the hard water is the best solution, regardless of the tank design, in a perfect world. Not all homeowners own, or properly maintain water conditioning equipment.

If you plan on investing in an indirect system, check and treat your water for the best performance and longest life expectancy.

Similar to changing the oil in your car or truck

hot rod

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Brad White_9

Mark-

Sorry about the jargon- MBH is 1000's of BTU's per hour.

True, most boilers get the summer off but with a low mass high pick-up boiler this ought not be problematic. A little exercise is a good thing, right?

Because you are bringing the boiler capacity to bear (either as a zone but best way using all of the capacity ("either/or" house or domestic), the recovery time is rapid. If the DHW is shared (parallel with space heating) the two might fight each other, drawing against each other. Yes it might slow down recovery so I favor a 3-way valve, all or nothing to DHW. If you go parallel with a pump for DHW (I prefer pump versus valve; you have the HP where you want it), make sure it is sized for proper (abundant) flow to the indirect. No wimpy stuff here, no trickles. I have used Taco 0010's with a 40 gallon SuperStor.


All such setups are known as "domestic HW priority" which means that the boiler over-rides any setback temperature to heat the DHW, then reverts to normal heating operation. So do not worry about that. Just make sure your controls respond to DHW priority.

The first hour draw: Compare spec sheets from each type and see. IIRC, a 40 gallon conventional will have a first hour of about 80 gallons depending on temperature rise. 40 of that is in the tank, the difference is the burner playing catch up as you draw it down. Some dilution negates some of that, true of all tanks.

A 40 gallon indirect can be in the 200 gallon first hour range. Boiler temperature and expected rise are obvious variables, but you get the idea.

Another point in favor of indirect longevity is that conventional heaters interface 2,000 degree flame and 400 degree flue gas against 40 to 50 degree cold water, separated by a thin metal tube, followed by cold room air up the flue after each cycle. Something has to give; that is an abusive environment for most metals. Indirects use 170 degree or so boiler water against the same incoming water; much less stress and no "airway" heat losses between cycles.

PJO_5

One more thing to consider...

is whether you may need a buffer tank. If you want to use one, the TT heaters have a few gallons of buffer for the Munchie to "push against" instead of less than a gallon in the coil.

If you want a lot of buffer, an Ergomax (or Torbomax as well?) might be the ticket...a coil sitting inside 26 gallons (minimum) of boiler water...now that's a lot of buffer. Plus, you avoid any issues of Legionella because there's no domestic water stored.

Take Care, PJO

Mark_46

Brad

Thanks, awesome info!


You say DHW should be, or is normally, priority...I’m growing more and more concerned. Here’s why:

As you may know by now ) I will use a Unico Hi-V system for both primary heat and AC. I’m already a little on-edge about pairing a Munchkin with Hi-V hot water coils. With less airflow in Hi-V the water coils start to lean towards needing higher supply temps from the boiler. The Munchkin of course like lower temps.

My house calculated heat loss is about 51,500 BTU/h (30K zone 1, 20K zone 2) which is 65% of the Munchkin 80M's capacity. Factor in the potentially higher temp needed for the water coils and it could be a delicate balancing act. But I have accepted that this configuration will work and take advantage of a condensing modulating boiler and also keep the house comfortable. I’m hoping to be able to dial in the Munchkin inlet and outlet temps at about 160 (out) and 140 (in) when all is said and done. Time will tell.

Now, to throw the final wrench into this configuration, tac on the indirect where the DHW would be priority when both call for heat. I am concerned there would be a boiler capacity problem? In addition, if the boiler starts to approach being undersized it would need to fire closer to 100%. Isn’t it less likely to modulate and condense as a result defeating the purpose of having such a boiler? I see the Superstor ratings are based on 180 degree boiler water! That is already considerably higher than what I hope the space heating design temp will be. Unless the Munchkin is capable of having 2 sets of inlet/outlet temps? One for DHW, one for space heating?

You indicate that piping the indirect with a valve vs a dedicated pump makes a significant difference. What i dont understand here is there is still one heat source regardless of how the DHW is diverted to the Munchkin. They would still fight for heat, no? The overall system design doesn’t make sense to me. Am I missing something? Your thoughts?

Robert O'Brien

Rick

The Weil is a Phase III.The Peerless is a Superstor.

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Supply House Rick

Maybe I'm Wrong but...

The Peerless and the Weil Mclain indirects & DHW coils were in the Triangle Tube Factory. TT makes EVERYBODY'S DHW Coils.

I could be wrong

Rick

Robert O'Brien

here's some pics

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Brad White_70

Well, Mark, let me see ...

I think the best way to explain this is that the time it takes to heat the domestic HW is limited. Maybe 10-15 minutes from a cold start and maybe 5-10 minutes to top it off, depending on draw at the time. And this occurs maybe, what, twice in the morning and once at night? Not a long time compared to annual heating hours.

Does it defeat condensing? For a short while. But when it starts to heat, there indeed is condensing while the Munchkin (or any boiler of this type for that matter) is warming up. When the two temperatures (boiler and domestic water) begin to converge, condensing slows then stops. So for your peace of mind, the condensing happens half the time in rough terms, even when it is seeking above-condensing temperatures.

Now, because you have a Unico hydro-air application, your supply temperatures on a design-cold day will be higher than if say floor radiant or panel rads. (You know this.) But you can still set it down to a point that your air discharge temperature begins to come out too cool. (Test and set, experiement a little to find the lowest temperature consistent with space comfort). Savings and a greater margin are yours. Your domestic HW will still thrive.

As for the "fighting" between the priorities, if you have a 3-way valve as I do, no contest, 100% of the boiler capacity goes to heating your domestic water. Thus your total time in the mode is held to a minimum.

When you "share", your home heat may call for X percent and your DHW gets the rest. If the house needs 50% then your DHW gets a lesser amount and takes longer to recover. At the same time, the DHW is calling so the house sees hotter water for the duration.

Because the Munchkin is oversized in your case, I am less concerned. It modulates down what, 5:1? So when you go back to heating you can fire to the load more of the time. You have no lesser Munchkin selection that will do it all. Keep in mind that on a BTU basis, your domestic HW is your largest hourly-rate load!

Hope this helps.

Brad

hr

I thought TT and Weil tanks

are made in Belgium and labeled to both? I didn't think the company was owned by TT?

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Mark_46

Overall

Brad,

It makes more sense now. As always, youre a fantastic source of info. Are you available for consultation work? )

So in your opinion does the overall system I'm describing pass the laugh test? That is:

1. Munchkin 80M with...
2. Hi-V heat and AC. two zones, one air handler for each zone. water coils for each handler with...
3. let's say a 30 gallon Superstor indirect?

clammy

muchkin /buderus

I only have a few munchkins that i have install for myself and a few other that i have help install for a plumber buddy of mine and he has used the htp super store while i have used a mix of mostly buderus st200 tanks and there budget tank which i am at a lose of memory for a model # but in my experences i have found the buderus tanks excellent with one point that htp and other do not have and that is a removable man hole for clening and inspection .That feature alone puts them on top and also with about a dozen of there tanks i have installed i have yet to have any issues with them and have not had one complaint about not enough hot watre .The rear piping pipng of there units is also a plus in my book leaving a better finished install look also . I have found that using a mixing valve to lower your draw temp in comparision to tank temp very helpful and on another note remenber to set the post circ time on the munchkin for a few minutes other wiuse you may be back for a nucines high temp lock out on the munchkin controler,but all in all i feel that the buderus line of indirects are a very well made tank and i ahve yet to have any issues with there tanks and boilers that i have installed .I have been using buderus boiler for at least 8 or 9 years and i have such faith in there product line that i even installed one in my parents home several years ago with out ant promblems thus far .Peace and good luck clammy

Mark_46

Another thought

Brad,

one other angle I've been thinking about. Do you think an indirect is more suitable for radiant floor or fin tube than hydro-air? Heres my thinking.

If DHW is priority as we've discussed then there is no heat dedicated to space heating during DHW heating, at all. But in a radiant floor or base board rad system, theoretically the heat could still be 'radiating' since the system is already hot even though its kind of cooling down. By the time its competely cooled (where no more heat is available to radiate) it is likely the DHW has recovered and the boiler can go back to space heating. In other words, there is less of an on/off effect with radiant than Hi-V. Your thoughts?

Brad White_72

The only way I would ever use an indirect or any domestic

hot water heater as a boiler is when it is serving only heating as a closed system. I would never, every use domestic hot water as a heating medium due to potential for Legionella and general oxygenation of my heating system materials.

You can use an indirect as a heat exchanger of course. If you use it "reversed" with the heat exchanger taking the radiant flow, the volume of the tank acts as a buffer. Good if you have low mass and short-cycling issues.

Remember, Mark, the time period of domestic water production, when the full boiler is dedicated pro tem to the task, is short. You may not notice it in the house. I never do.

J.C.A._3

To add to Brads post....

What I said in my original post...If you know the times everyone is going to wake up, and program thermostats so the heater is only needed for HW production...you're in the clear. If the times vary on off times, (weekends and holidays..), the recovery time will hardly be noticed unless you're trying to fill the Jacuzzi at 6 in the A.M.or 1 in the morning, for some inappropriate time....Hope it IS the only reason for any discretion, and ..heck, you'll be in the hot tub anyway....the heat can wait....right? Chris

Mark_46

Sorry, I didnt explain it correctly

JCA, Brad,

I think I messed up explaining this one. I am not suggesting using the DHW reserve for space heating...no way.

What I meant was with radiant (floor or Baseboard) systems when the boiler switches to heat DHW, those type of emitters could continue to give a little heat while the boiler is 'focused' on DHW.

With a hydro air configuration, I assume the boiler switches to heating DHW and the Hi-V air handler blower motors turn off, no? If thats the case, theres 0 space heating during DHW heating. Radiant could still throw off a little heat during DHW heating helping to sort of bridge that gap before the boiler can switch back to space heating.

Mark_46

Not sure I understand

JCA,

I would think that after 'wake up' (human that is) both space heating and DHW will be needed.

Brad White_72

Mark

When the DHW is calling, the air system can and should continue to run. No need to shut off the fan.

It will deplete the residual heat in the coil. With radiators, in-floor heat and panel radiators this is less of a concern than with air coils which have lower mass. There would be zero heat "added" to the heating loop during that time, but remember the time period is short.

If any concerns re: mass and carrying you over the DHW heating hump. When DHW is done you are back in business without a hiccup.

Mark_46

Oh

Brad,

I assumed the Hi-V blowers would be turned off. OK, so that wouldnt be nearly as much of a concern. However, as you say, the resideual heat in the coil would be depleted. I guess that could lead to perhaps cool (or less than hot) air coming out of the registers. But I guess it wount be very pronounced and the frequencey of this happening would be low, correct?

J.C.A._3

Mark,

Like you figured, and Brad implies, is that you heat the spaces to "comfortable levels" BEFORE you know you'll need the DHW makeup. Programmable thermostats are your friends...as long as things don't vary too much, with any type of emitter. Key is to either learn, or get the thermostst to learn the cycles. Confused? Some thermostats DO learn ! Surprise! Chris

Mark_46

Ah ha

JCA,

I see. Now I understand with the illustration you gave.

Brad White_72

As Chris said

Getting the house warm in advance is key. The mass of the house will hold in the interim. Air systems, as I mentioned, might benefit from a buffer tank (hydronic piggy bank) to ease any dips. That is the thing about air heat. It is volatile; it heats and cools quickly compared to water in radiation (mass).

Try not to over-think this, Mark, really. LOTS of houses do this with no issues. Like the bumblebee, there is no way on paper that any aeronautical engineer could justify it's ability to fly. "Yet the buzz along merry in their ignorance." (Attributed to someone unknown to me.)

EDIT: Chris is faster on the keyboard. Says more in fewer words!

Mark_46

Thorough

Brad,

Ya trying not to over think...I prefer to think of myself as very thorough ). I try to 1) understand and learn and 2) make sure all the angles are covered. I trust the installer i've hired but I also feel there is a natural conflict of interest when the system designer is the same entitiy that is selling and installing the equipmnet. Just business. Protecting our investment. Plus, every time there is something new to consider, its typically something a home owner has no previous experience with. So it tends to start a whole other learning curve.

This is probably the single largest investment we'll ever make in this house (and its no small investment) and I want to get it right and as error-free as possible. We're not doing this system with selling the house in 3 years in mind. We plan to stay!

As far as 'air heat', ya its a bit of compromise. But I actually grew up in a FHA house...no real complaints. I wish I could install a state of the art system but the exisiting house doesnt allow in temrs of cost benefit. unfortunately there is a point of no return. So i'm trying to do the best system within reason.

Brad White_72

Thorough

Hey Mark-

No worries on being thorough, you are wise to be so. I too am thorough in a similar way, so I fully understand. Part of this challenge was the teaching or explaining what may be complicated concepts at first. Chris got the point across with his programmable thermostat explanation. But you do think of things from all angles, lots of "What-Ifs" and that is always a good thing!

I just did not want you to get wound up on something that should not be a problem -free you up to think of other things, figuring this one would take care of itself.

The notion of designer/installer may seem to be a conflict at first, but I see it a little differently.

Being on the design-side, so I come up with what I think is the best design/system/concept for the Owner and their situation. The contractor installs it and the owner gets my ideas without the contractor's prejudices, let's say.

But here is the flip side and is predicated on the assumption that the designer/installer is experienced, competent and "one and the same":

He/She is responsible for EVERYTHING. If the design is flawed, no amount of field work can fix that. If the execution of a good design is flawed, that too is their responsibility.

Once you find such a pro it will all come together. Glad you are sticking around and living with your investment!

Brad