water heater for radiant and dhw

Mark Eatherton1

The Munchkin is so efficient that it produces an acidic condensate. This condensate will destroy the mortar typically used in conventional brick chimneys. Therefore, you have to use non foam core plastic pipe. I used PVC, I think a person could use ABS. You can use the chimney as chase, and draw the combustion air down through the chase, thereby recovering additional waste heat and further increasing the efficiency of the appliance.

A buffer tank may not be necessary depending upon the system design and base loads it will see. I may end up putting on one mine but it has more to do with configuration than it does the appliance. If you needed a buffer, it would be in series with the loads.

Mine will be parallel, but again that's just me, experimenting with my own system.

As for indirects, I like Heat Transfer Products line. They also make the Munchkin. I've also used the Buderus tanks. Built like a German Panzer tank. More expensive, but you DO get what you're paying for.

If your bathroom is radiant floor, tube in cementitious material, you probably won't need a buffer tank. If it's base board, you will.

Thanks for the kudos.

ME

andrew_3

Water heaters for whole house

Anyone any opinions on using a large water heater such as the American water heater co's Polaris as the sole source for a new construction? I will have about 5000 ft of heated floor (including basement). The house is 4 beds but only 3 occupants for the DHW load.

bigugh_4

Your self a favor!

never use the same water for both domestic and heating. Note "The Same water". Keep potable water seperate from heating water. There are just too many conditions that can compromise potable water and make someone sick!

andrew_3

same water

Thanks biguh. Can't imagine why anyone would use the same water although there are some radiant heat websites which espouse the idea. I'm talking about a water heater and a heat exchanger to run the radiant. It's the reverse of a boiler with an indirect tank.. you are using your heat source to heat and store the large volume side of the system (the DHW) and a heat exchanger for the relatively low volume radiant pipe. Why not?

bigugh_4

that stated is done quite often.

And has been for a long time. The thing here is the amount of heating needed and for how long. Water heaters are not that efficient, and not built for space heating. However in some cases it is done. My point is; as a plumber~~~Keeping potable water clrean and safe!

andrew_3

Which boiler

Point taken. I have posed this question on another board and the overriding feeling is go boiler and indirect and leave the experiments to others! So... I bow to the professionals!
Now any views on condensing boilers?

bigugh_4

Now here I bow to the

the my ols self! I like it as simple as possible. Condensing is not a simple boiler. Are we being led down a path of failure when we need heat most. A circ pump goes bad! A exhaust blower quits. a t/s gets hit by the kids ball. a zone valve sticks shut. The more bells and whistles the more one is going to need the repairman & or parts on hand. and has been said, Installation is 95% of the job. just brain storming here with you! someone once said there are three ways to do a job, Fast, Cheap, and Excellent. Pick any two!

Mike T., Swampeast MO

Properly installed in a good system their efficiency is so high as to interest even the most skeptical.

The real question is their longevity and are still new enough that there is no true answer.

You will get as many preferences as there are condensing boilers.

hot_rod

Actually

The Polaris is a very nice match for low temperature radiant. The 34 or 50 gallon tank offers a nice built in buffer, and they can easily have a HX mounted externally to supply radiant and dhw from the tank as seperate systems.

The main hang up is they are not listed for radiant heat applications. Last I heard Polaris would not approve this use, and warranties may be void if used this way.

I have a number of them installed as DHW units with the external flat plate hx and they work great. Efficient, small footprint, etc.

If your system run temperatures below 140F, there are many condensing boilers available, that have the correct listings for code approval. Munchkin, Weil Ultra, MZ, Viessmann are a few of the more popular. In some multi zoned applications a buffer is still a nice option. That, to me, was the beauty of a tank type condensing heat source.

The above condensors have the ability to handle indirect DHW options also. Most are built in to the "on board control" If the low temperature radiant is the big load I feel the condensors make more sense than a cast irom boiler that needs to run 160F.

hot rod

andrew_3

not listed for radiant heat applications.

Thank you all for your insights. The above quotation by hotrod makes me more certain I should go boiler! I think it will be a munchkin or an Ultra but will wait to see the quotes.
Now some more words from the wise!!
Do I need a slab sleeve for the basement thermo? I will have half the basement for mechanicals and storage and half as a finished room. Are 2 zones an overkill on that floor?
I have read of needing a control like a Tekmar 260. Is that relevant in radiant since radiant has a slower reaction time than forced air?
Should you zone with small ciculators or with motorized valves.
Hotrod I hate to show my ignorance but what is a buffer?

Mike T., Swampeast MO

Buffer

> Thank you all for your insights. The above

> quotation by hotrod makes me more certain I

> should go boiler! I think it will be a munchkin

> or an Ultra but will wait to see the quotes. Now

> some more words from the wise!! Do I need a

> slab sleeve for the basement thermo? I will have

> half the basement for mechanicals and storage and

> half as a finished room. Are 2 zones an overkill

> on that floor? I have read of needing a control

> like a Tekmar 260. Is that relevant in radiant

> since radiant has a slower reaction time than

> forced air? Should you zone with small

> ciculators or with motorized valves. Hotrod I

> hate to show my ignorance but what is a buffer?

Mike T., Swampeast MO

Buffer

Not Hotrod but a buffer is a BTU reservoir.

EXTREMELY useful in highly zoned systems where a small zone can cause terrible short-cycling of the boiler.

Also VERY useful in high mass, conventional boiler systems when the buffer becomes "one" with the primary (boiler) portion and the secondary uses injection mixing.

bill clinton_3

Polaris/hx

Andrew: I'm not sure what Hot Rod meant by the "not listed for radiant applications", but I think he meant it is not listed to be used for heating alone, but is fine for combination domestic hot water and radiant (so long as you use a heat exchanger!!).

If I were going the high efficiency condensing route, I would choose the Polaris with external plate heat exchanger every time: the reason is the "buffer" which eliminates a lot of difficulties. I've been doing this for probably fifteen years with pretty good success: have probably installed forty or so this way. Polaris is pretty reliable--the main issue being ignitors which tend to go out every couple of years. Have only seen two leakers, one after ten years, the other after two years.

That said, if you are looking for a good balance of efficiency, reliability, serviceability and longevity: Buy a Buderus cast iron boiler. These days, that's my first choice and my guess is that over a period of decades, the total cost, including fuel will be less with the Buderus. The hassle factor will be even more in favor of Buderus.

Bill

hot_rod

More thoughts

how will the additional basement space be used. It is very easy to install the tube to allow zoning later on. It could be all loops with ball valve on the manifold to allow manual zone control for now, then telestats added later for more comfort zoning.

I would use a slab sensor well for bathroom areas, for sure. This allows finer control and gentle floor warming ability. For bedrooms a wall "air" stat would be fine, in my opinion. Again, install the tube so the bathroom, if any, could be split from other rooms, as with sleeping rooms for individual comfort levels.

Look deeper into the Munchkin. The Vision control will do many of the functions previously furnished by aftermarket only controls. There are more secrets in that control yet unlocked!

Some of the postings of graphs from ME recently are part of the data logger built into the control. You need to be certified to acess this feature with a laptop.

I generally zone with valves. On the size jobs I do one circulator is plenty for the loads. Seem silly to install a circ and throttle away most of it's power, force it to run way down curve, inefficiently to handle small zones like bath or bedrooms.

A pressure activated bypass is an inexpensive control to add to zone valve jobs to keep the circ "in line, and on curve" better.

Have fun in your quest for the best!

hot rod

Mark Eatherton1

Do I have a view of a high efficiency \"converter\" for you...

Jeez, Thanks for asking!!:-) Welcome to The Wall. If'n ya don't learn something new every day, you were either A; Not paying attention, or possibly B; Gone fishing. And if'n ya was B, Gone Fishin. and ya didn't learn something new, you was A, Not paying attention!!(Thanks Dad ;-)

Ultra high efficiency equipment is not unlike highly efficienct automobiles. They're maintenance intensive, but in my opinion, worth it. I've seen them now for about 4 years, and they've been around much longer than that in Germany. I saw them in Germany 7 years ago, and I think the big V has been doing it for 11 years. My guess is that it CAN be a 20 year boiler. At the pace technolgy is moving, you WILL want to change it out in 20 years anyway..

Remember maintenance. If you ignore them, they WILL go away. But peoples basic needs for efficiency and comfort CAN and ARE met by them. I know because I live with one. I can tell you to the tenth of a degree what's going on in my system. Not that you'd really find it interesting, but believe me, I do. More on that later.

I've installed both the Munchkin and the Vitodens converters. I call them converters because they're really not your old concept "boiler". Although they CAN boil. That'll make your sphincter pucker! Makes your feet want to run too. Anyway, they are not a simple machine. They require set up tools and knowledge far beyond that of the mortal typical plumber/hot water heating person. When I ask outloud at the heating counter of my local warehouses if anyone is doing combustion analysis on their start ups, I get blank stares...

I've personally seen these converters running at 100 % efficiency. Just for a few seconds mind you, but it did read 100 %. Heck, with the combustion air being drawn from the attic, and the sun preheating the air, these units could easily be over 100 % efficient! Especially if compared to the typical atmospheric American burner. Too much uncontrollable excess air. I think the Germans have improved the operating characteristics of their typical atmospheric burner, but nothing beats modulation..

And the control logics behind them, UN BELIEVEABLE!!

I'm "Base loading" apartment complexes DHW system and space heating systems with the technology and reducing the fuel bills by around 50% versus your typical american horizontal tube boiler (Ajax).

The technology is here to stay. If you're in the heating business and haven't aligned yourself with the technology, you're behind the 8 ball. Some old timers refer to them as "throw away boilers". And if improperly maintained, that may be true. But then again, I remember Doc Ball telling me he loved a Blood and Gutss 100 pump "'cause it TALKS to ya before it dies!" and I remember mumbling something about not wanting to hear it talking clear down the street! He then proceeded to remind me that "them car tridge pumps'll go out like a light bulb." He had a point there...

Anyway, I digress. I love my lil Muncher!! Find a good trained installer for whatever product you decide upon..

I guess I'd have to thank Pete over at Monitor products for getting me interested in the technology, and the MZ boiler he donated to the school. Thanks Pete!


ME

andrew_3

chimneys

Thanks again everyone. Mark nice job. Wish you were local! A post by Gary wallace on 14th Oct. (In the middle of the Buderus thread) suggests a chimney over a direct vent system. Would that work on a Munchkin? Do we need a buffer with the Munchkin and if so how do you pipe it? I can see the small zone in my master bath short cycling to keep my tootsies warm!!! Also any preferences for the indirect?