Munchkin Contender vs. Munchkin regular

Unknown

FYI,
I have not had the pleasure to install one yet, but the Contender has a lower AFUE rating and will not qualify for the federal tax credit.

Contender is 93% and the Munchkin is 95.1%.

bruce_21

Has anyone had experience with the Munchkin Contender? I put in a regular T50 for a customer last year we both love it. The Contender looks to be 25% less upfront and this client has a tight budget so it looks real good on the surface. Are there operating differences, more cleaning or other "hidden" negatives I should be considering? Thanks in advance for any advice.

Ted_9

MC vs. M

Well, I like the new Munchkin Contender. One thing to note is that the MC does not have an ASME rating. It also does not come with the Vision 1(out door sensor and indirect hot water sensor). However, you can buy the Vision one and hook it up.

What's nice about the Munchkin Contender are the new sizes. They come in the MC50, MC80, MC99 and MC120. The display board is mounted on the front of the unit for easy viewing. The cover comes off to expose 3 sides of the boiler as well.

Whichever one you choose, just make sure it is installed per the installation manual, as with any boiler

[Deleted User]

THe biggest difference...

The Contender uses a carbon composite water jacket, as opposed to the M series using stainless steel. The reason you can't get the ASME rated Contender is because ASME does not recognize non metallic water jacketing on "boilers", hence the appliance is only certified as a water heater.

I was extremely impressed with the new controls/wiring configuration. THis company has come a long ways in a relatively short period of time. I have a prototype in my own home that has a secondary heat exchanger built into it that scrubs the flue gas for additional BTU's.

ME

Ted_9

Tax

Good point. I would do the ODR anyway and 2% afue doesn't relate to much money. You could probably make that difference up by lowering the water temp a few more degrees.

[Deleted User]

Funny thing about AFUE and modcon boilers....

Viessmann and numerous other manufacturers modified their numbers to make their boilers comply with the rediculous tax credit standards. They didn't really do anything with their equipment, just went back and modified the math...

The tax credits are slightly better than a sharp stick to the eye. I don't even bother to mention them to my customers.

If I can't justify doing what I am doing without some sort of subsidy, I'm doing something wrong. This is one place I'd rather see the government NOT get involved, other than dictating higher required efficiency standards, which they just recently blew...

ME

bruce_21

What is this carbon composite water jacket? Is it exposed to the flame? If it is some sort of plastic, won't it burn out or melt away? What sort of guarantee do they give on it.

[Deleted User]

Water side only...

Fire side is same SS Hxer that Gianonni has been producing since, forever...

However, that said, from what I understand, there are internal combustion engines with carbon composite blocks. Not sure if that part is under fire or not, but it is known that those blocks do get rather HOT.

Only makes sens that it could/should be used in a water heating situation.

ME

Expert

Contender Boiler

I have many Contenders installed without trouble.



HTP was the first big player using the Ginanni HX.



It really doesn't need an ASME.  Since it is low pressure and very low volume this threat of explosion doesn't exist.



Over-sizing and poor system design will kill AFUE, real or imagined.



A great, quiet boiler with low minimum fire and small enough for the more modest home. If they would just stop selling them on the internet.

TMorg

Non-ASME

Non-ASME might be allright in your area or not mean anything to your customer but I can tell you in my area they are be forced to remove them regardless of when or how long they have been in service. It is still CODE in many areas. Even in rural areas I've seen removal orders once the use changes or an inspector shows up for something else. A local church purchased a house next door and because the house now has a secretary there during the day the boiler must have ASME rating. 5year old boiler which was in the house when it was purchased must be removed. A water heater is not a boiler! Tankless heaters being installed for heating appliances are being red tagged all over our area. It has taken the inspectors a while to catch up to what should have been disallowed all along. Just because it is promoted doesn't make it allowable. I wouldn't want to be the guy in court pleading "I didn't know" The answer I heard from a local inspector was "you are the professional, Now go put the correct appliance in and don't charge the owner for your mistake"  

CMadatMe

Viessmann

Mark could you further explain how and what numbers are modified?  If they were not modified what would be the true number? Personally I feel that the AFUE lables on mod/cons should be changed on all of them.



The label should show a operating range, 86%-95% with a statment that says something like. This boilers operating AFUE range is dependent on proper system design, installation and outdoor compensation.

ModConPro

What's in a name?

The water doesn't care how it gets heated.



Unlike a "tank-less water heater, the Contender is "purpose build" for space heating. The only difference then, is the no extortion was paid for an ASME stamp. This is a commercial standard misapplied to residential "pressure vessels" in some jurustictions. Since the heat exchanger is low-mass and very low water content, the ASME adds cost (about $1000.00 retail) without adding value to quality or safety.



The Contender boiler shares the basic Giannani heat exchanger with the majority of US "re-assemblers" and looks remarkably like the Viessmann Vitodens! Both boilers have a primary heat chamber (no plastic).



Many tank-type  "water heaters" are listed and accepted in the ICC "suitable for space and water heating". Stand-alone water heaters, be they tank or tank-less, are not allowed. The reason for this is the special care that must be taken to make this sort of installation work properly and safely.



Disallowing the Contender for lack of an "H" stamp is simply restraint of trade at the manufacturers level and blind faith - to be kind - at the contractor level.



The code officials mentioned here are not catching up rather, way behind as usual.

CMadatMe

Viessmann HX

Trying to compare a Viessmann HX to a Giannoni is a grasp. It is in no way even close. I can fit a Giannoni inside the Viessmann HX. They are also very different in material and gap

TMorg

ASME Giononni

My understanding is that if you order a Giononni heat exchanger from giononni for ASME they use a thicker wall heat exchanger to handle this higher pressure test. While it won't offer higher efficiency it may give you longer life. To say that it is just a payoff is a little deceptive IMHO. 

Steve Ebels_3

This is a joke.......right?

Mentioning Giannoni and Viessmann heat exchangers in the same sentence?

Jean-David Beyer

A few degrees? I wonder.

" You could probably make that difference up by lowering the water temp a few more degrees."



With my outdoor reset boiler, the reset curve starts at 75F until the outdoor temperature gets down to 56F. Then it goes up linearly until it is 0F outside, by which point the water gets up to 120F. Since the design day around here is 14F, I do not suppose it ever gets up to 120F. At 14F, the reset curve is at 109F.



Since my outdoor reset comes with the boiler, it might as well be hooked up. So the fact that the efficiency goes up only 2%, or whatever is is, is not a big concern.



But I wonder if the efficiency is that low. If I look at the graph (3-10) on page 48 of John Siegenthaler's big book, it seems that with a return water temperature of 70F, I could expect an efficiency of almost 98%. With a return temperature of 110F, I can expect an efficiency of around 92%. At my design day, I can expect a return temperature of about 110F. The difference is around 6% (condensing boiler).



This relies on two assumptions.

1.) The efficiency curve of figure 3-10 applies to my boiler.

2.) The supply temperature and the return temperatures are the same.



1.) I do not know how closely my boiler's efficiency curve matches figure 3-10, but lacking any other data, that is the best I can do.

2.) This is conservative, since I assume that the return temperatures are lower than the supply temperatures (or no heating would be going on). When the outdoor temperatures are moderate, I am surprised at how small the temperature drop really is (a degree or so). I infer that my circulators (Taco 007) are somewhat oversized for my 1100 square foot house.