Munchkin Boilers

Robert O'Connor_3

I have a new home with radiant floor heat. My plumber installed a Munchkin boiler with a side arm (45 gallon hot water heater). He said that the combination hook up would provide unlimited hot water. I have a 65 gallon whirlpool tub which I can only fill half way before the water becomes cold. Is there anything that can be done to help me fill the tub completly with hot water?

My plumber suggested a tempering valve. Or a larger 85 gallon sidearm which would cost another 1,000.00.

I am disappointed with my boiler performance in this area.
Thanks,
Darrell

Corby

Munchkin Boilers

I am currently doing a 15,000 sqft residential radiant floor heating job. I am wondering if anybody knows what is the best piping, and control strategy for this job. It is going to be getting 2 munchkin 199,000 modulating boilers piped in p@s arangement without mixing using two Tekmar 369 zone controls and a tekmar 2 stage boiler control. I would appreciate any info on the piping and control strategy for this job. For some reason I am having a problem visulizing how the control will see what water temp it needs from the boiler/boilers if it is modulating and it worries me that it will fire both boilers at once if only a small heat load is happening in the building example say one zone calls and the temp is not changing fast enough for the heat load and it calls for the other boiler to fire. Also what about A DHW demand. This is my first time using Munchkin Boilers And I do Not Quite Understand the Sequence of operation. Any Comments would be very useful. Thank YOU

john wood

Munchkin looks at supply temp and return temp and makes a decision on how much gas to feed the boiler. It will always seek to supply the temp that you tell it to when you set it up and modulate based on return temp.

To use 2 stage tekmar, make sure you set the differential between the boilers at a high enough level so you do not get two of them firing every time and short cycling. On a concrete floor, I doubt they will short cycle tho.

If you do Indirect, you will have to run the boilers at a higher temp, usually 180F and mix down the temp with another control or valve. Tekmar 370 will do injection and indirect and i think 5 zones.

dzis help?

Wayco Wayne_2

You may want

to investigate the Munchkin Vision control to give you the different temps. You add it to the existing control and then you have outdoor reset and many different setpoints depending upon needs. Perfect if you have an indirect with a radiant floor and baseboard. (3 different set points)

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Matt Connolly

Based on the last post..

Why are you using a Munchkin if it's not going to condense? Since the Munchkin modulates to temperature and not to load, and can't tell the difference between a radiant heat call and a dhw call, why bother? You'll be running it at high temp all the time and mixing it down for radiant. A good cast iron unit will do the same thing.

If you want a true dual temp boiler, try the Monitor MZ line. They can run low temp all day in full condensing mode, then ramp up to 180 for dhw recovery. They are reasonbly priced and save a fortune on labor to install. Check them out at www.mzboiler.com , or email me for more info. I've had one in my house for 4 years now, and have installed many over the years.

Matt

munchkin-man

Munchkin controler is the 925

It has the ability to add on to it. This is called the vision one. Go to www.htproducts.com click on the 3d Munchkin boiler and go to installation manuals select the vision one manual and read up on it a bit. It wil be helpful if you print it out and the 925 manual. After reading them give tech support a call and we can walk you through it. The staging of the boilers can at this point be done using the differentail setting. In the future we will have controls that can achive this. Thanks for your interest in our products

john wood

It will condense!!

Munchkin will condense at 180F so use it.

Ted_5

Will not condence at 180F or even 140F

Look it up. If you have the best air to fuel mixture the
flue gasses will start to condence around 135F.If you don't
have the wright mix it might need to be 120F. It doesn't
matter who's boiler it is!

john wood

Then what is that stuff???

I see a clear liquid running out of the tube in the back of the boiler on baseboard jobs running at 180. If it is not condensate, what is it?

Munchkin is rated at 92%AFUE and that is well above the recognized condensing point. What folks don't realize is that there is a two stage heat exchanger in the Munchkin. Single stage units (like the MZ?) will not condense at 180 but munchie will.

Mark Hunt

You are correct John

Them laws of physics are just that, LAWS!

Perhaps I should start posting the customer responses I have gotten on EVERY Munchkin install I have done.

A word to the wise,

you better know what you are doing before you step into this arena. This goes for any high end boiler. If you think these boilers are no different than the stuff you are used to installing, you are sadly mistaken.

Cross your T's and dot your I's.

In the mean time folks,

pray for our troops.

I love what I do, but I couldn't do it without the men and women that are standing at hell's gate.

I support the decision our president has made and I believe that our cause is just.

God bless America and God protect our troops!

Mark H





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tombig

Condensing?

The Munchkin man posted here so I hope he returns to answer this. I am exploring this new technology in detail and from what I've gathered any condensing boiler will not condense at high return temps. 92% is just a benchmark at test conditions. At extremely low inlet temps I'm sure the Munchie far exceeds that. Conversely, at high inlet temps it drops to 92% or maybe below. How could flue gases be condensing at high inlet temps like from baseboard except at start up?

I've got a Godson, a brother, and a nephew who may or may not be in harms way as we speak. God protect all our brave troops.

Tom Goebig

Mark Hunt

Condensing

What does it matter where the condensing takes place?

The fact is that boilers like the Munchkin and the Vitodens extract so many BTU's from the flue gases that it WILL condense at some point and at high temperatures as well. Take a 90+ efficient furnace, does condensing primarily take place in the heat exchanger?

I have NEVER seen a stack temp higher than 110 degrees on a Munchkin boiler. I have them installed in just about every imaginable scenario and there is ALWAYS condensation. I am sure that the Vitodens and the other like designed boilers do the same.

Take a good look at the design day criteria for your area. You will see that the majority of the time you will be able to handle the heating load with LOWER operating temps. I don't care what the system is, it was designed around lowest outdoor temps!

So all this hoopla about "true condensing" is BS unless YOU design the system to heat a structure with low temp water to begin with.

I have customers who have had their heating bills cut IN HALF since we installed the Munchkins and I am sure they would have seen the same result had we installed a Vitodens or even a Weil-Mclain Ultra.

Sealed combustion units LOWER depressurization thus lowering the infiltration to the home. THIS IS A DIRECT ENERGY SAVINGS!

IMHO, there is absolutely NO reason to install anything but sealed combustion, CONDENSING, boilers today. Modulating gas valves, outdoor reset, all these things save money and fuel, WHETHER THEY CONDENSE IN THE HX OR IN THE FLUE! MONEY SAVED, RESOURCES SAVED!

There are those who, "can't justify the increase in price", well they haven't tried. Again, IMHO, our industry is so stuck in the 1950's it isn't even funny. There was a post here not too long ago from a pro that said he would wait 10 YEARS before he tried a "new" idea. In 10 years it will be old technology and probably obsolete!

I'm going on the record here to say that I do not care where condensing takes place, as long as it TAKES PLACE! P/S piping was designed specifically to PREVENT this with the "old reliable" technology.

It's time to step into the 21st century folks. It gets better every day!

As for our troops, soon the people of Iraq will enjoy a freedom that they have NEVER known. All thanks to the USA and our allies.

I posted resolution 1441 in another post and I hope you all read it. It laid out the ground work for where we are today.

The tyrant of Iraq has defied and scorned the will of the UN for 12 years. He has used chemical weapons against his own people. He has invaded two nations. HE has brought this upon the world, not our President. All that said, we as Americans need to unify tonight. The political BS can come later but right now our troops need to know that we love them and support them. We will soon find out whether Iraq has the WMD's they say they don't or not. My guess is that he does and he will soon use them.

God protect the innocent, God bless America!













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ken_6

p/s condensing

mark,

if p/s was to help protect cast iron equipment from condensation would you then leave it out to help promote condensation on a munchkin?

thanks
ken

Mark Hunt

Yup

But we need to understand flow rates through these low mass boilers.

There is very little mass (water) to absorb btu's in the HX at any time so we need to provide proper flow for proper heat transfer.

The new Vision control from Munchkin will allow us more flexibility when it comes to installing these low mass systems.

Match your flow requirements with your heat requirements and you will be just fine!

Mark H

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Troy_3

Condensing Munchkins

I will second that Mark. We have installed many different applications and these babies always seem to condense. We even have some high demand DHW jobs that still condense all summer. And I'm talking a lot of condensate. I know because I had a couple condensate tubes come out of their holes and flood the basements. Figure all you want- we have seen it. But if you are afraid- don't worry Mark and I will pick up the work. The model A Ford has a crank start so you don't have to worry about that battery being dead. Now that is proven technology. Just kidding!

heatboy

How?

Does Monitor have some special dispensation from the laws of physics? If it can do what you say, that's great! I need to know how before I start informing clients of this.

hb

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Matt Connolly

Laws of physics the same, controls different..

The Monitor has 2 seperate temperature settings. In the normal heat mode, the MZ, when in a properly designed radiant system, will operate off the low temp aquastat all day long, condensing properly. When a high temp or dhw call comes in, the unit switches to high temp mode and runs up to 180. It will condense until the return water exceeds 127F, then condensing on the HX, which is the only place that counts, will end. The unit will still be at 92% efficiency at this time, not the 96= during low temps, but you know that, Jeff.

Matt

Matt Connolly

It totally matters where condensing occurs...

when efficiency is concerned. If you can't put the benefit of the endothermic process (condensing) back into the heat exchanger, and thus into the home, then there is no benefit! (Sorry for the "thus", but I thought it made me sound smart) Anyway, condensing positively ends at 127.4F for test gas, so any return water above that in the HX will not turn vapor into water, which is the endothermic process (sorry again) that is known as condensing. If it happens in the flue, it is only because the flue walls are cool enough for the condensation to occur. Other than a warm flue pipe, how does this help?

The primary / secondary piping often used with the Munchkin and other units that maintain a high temp primary and mix down to varying degrees cannot condense with any benefit since the return on the primary is well above 127, often closer to 150. This is one benefit of the MZ, since it has a very low head loss hx, it doesn't need p/s piping except in very high gpm applications, and the temp set on the unit is the same as the temp for the heating supply. The outdoor reset allows any temp in the design. When the high temp zone (if any) calls, the MZ diverts flow and ramps up temp to 180, or wherever that range is set to. The laws of physics remain intact.

Matt

Mark Hunt

But

the flue gases WILL be very low Matt. Otherwise we would not be able to use PVC pipe to vent it. Right?

So where did the heat go? As I said, I have never seen a stack temp higher than 110* in a Munchkin. I have not used your product, but I would imagine the same thing happens with the MZ.

Lower stack temps indicate more BTU's have been extracted from the combustion products.

Mark H

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Ted_5

AFUE bench test

is standard for all boilers,140F supply and 120F return. If
your system has higher water temps are you getting AFUE? On
a condensing boiler you get add points for the amount of
condesate.Thats how we see AFUE above 90%. I know that the
Vitodens has an AFUE of 94.2% with a control that has 3 temp.Boiler temp.,low temp. w/a motorized 3 way and ramp up
temp for dhw. In the two smaller models it also has a built in weather reasponsive pump[K-M Bus pump]All this adds up to
94.2%

kf_2

Mark Hunt

Mark,

You are right about the low temps flue gas, however, if all the condensing is happening in the flue and not on the fire side of the heat exchanger you are NOT transferring the latent heat from the flue gas back into the boiler. It is just going down the drain with the condensate.

Also, to your comment about condensing gas furnaces; they condense more often than boilers because the return air is usually below 75 degrees. Way below the 136 degree dewpoint for natural gas.

Don't be fooled, fire side condensation (the only place it counts) can only occur when the return water temp is below the dewpoint of the fuel being used. (136 degrees for nat. gas at a 10.5% CO2)By the way, I don't think the munchkin can even achieve 10.5% CO2. That means the dewpoint becomes even lower and harder to reach.


kf

Mark Hunt

My point


is that these units still produce low stack temps.

The Munchkin boilers are extremely efficient regardless of what the operating temperatures are, just like the Vitodens and the MZ.

Every customer that we have installed a Munchkin boiler for has reported huge savings on their gas bills. I do not care whether it's a baseboard system, radiator or radiant. Granted, efficiencies go up when we lower the operating temps of the system and if you get to design the WHOLE system from scratch you can do this.

Even in retro-fit applications the original systems were designed for worst case scenarios so that the MAJORITY of the heating season they are over sized and inefficient. Incorporating outdoor reset in the new installation will allow the system to operate at those lower temps for much of the season. Can't do that with traditional boilers without protecting them from those lower return temps.

My customers that have systems that will operate with high temps during some of the season really do not care where the condensate is coming from, they LOVE the low fuel bills!

Mark H

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tombig

Efficiency


I've heard that condensing boilers can get up to 98-99% when return tempsare low. I'm sure the low stack temps at 180* are due to modulated low fire. More efficient than a standard boiler either way. I saw the Weil Mclain Ultra the other day. Impressive unit. Dual temp w/reset right out of the box.

Matt Connolly

Not only are you right,

but you are exactly right! Heat exchanger condensing (where the heat transfer goes to the system water supply) is the only kind that counts toward efficiency. If you are condensing during the end of a dhw cycle, the only way that can be beneficial is if the dhw temp is at 120 or below. Condensing in the vent, while occurring and draining out the cond. drain looks like the unit is in condensing mode, it's reaaly not.
Matt

Howard

OK now u got me all confused

If the products of combustion exit the boiler at 120' or less and the return water enters the boiler at 160' or more, how do you get that last bit of heat out? It looks like quite a challenge to keep the return water from re-heating the flue gases.


Howard Hansen Service Technician Allconfused

Mark Hunt

Matt


Are you saying that the MZ should ONLY be used in low temp applications?

If that is the case, you have just removed it from the MAJORITY of heating systems in North America.

What is your point?

Mark H

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kf_2

Mark

Nobody is saying that condensing type boilers should only be used in low temp or condensing type applications. The truth is that the majority of heating systems (new or retrofit)with outdoor reset, will probably be in condensing mode for a majority of the heating season anyway.

The thing that frustrates me is the hidden marketing that implies that certain boilers defy physics and mother nature by saying that they can achieve fire side condensation and 90+ efficiencies in non condensing or high temp periods.

The fact is that if you look at the fine print of most of the manufacturers literature you will find that most don't even condense on the fire side until way below dewpoints. For instance Matt Connonly states that his boiler will not condense until return temps are at or below 127 degrees. 9 degrees less than the 136 degree dewpoint for natural gas. Mainly due to the burner not being able to achieve 10.5% CO2 ratings.


kf

Matt Connolly

My point is...

That any condensing boiler will be the most efficient the lower the return water temp. A properly controlled one (with outdoor reset) even with hwbb will condense 90% of the heating season. This goes for a Munchkin, MZ, Vito or whatever. Low temp simply maximizes. The AFUE for the MZ at DOE test lab is 92%. It is virtually impossible to get any higher at that spec. Remember, the non-condensing cast iron boys made up the test for the gov't. They had to cover themselves. At typical radiant temps, the MZ is 96.6% efficient.

Two points to address also: You mentioned the Munchkin has 2 heat exchangers. Where is the other one?

Also someone said the AFUE is 140 out, 120 return. How can that be - that condensing return temp area. I thought it was 180 out, 160 back.

Matt

Mark Hunt

Uhhhhh....


I never said that the Munchkin has two heat exchangers because it does not.

Regarding the higher efficiencies with lower water temps, I doubt that there are any contractors here that do not know this already.


How about we agree Matt, that the new technology offered by SEVERAL different manufacturers has challenged the "good ole boy" mentality?

After you have been at this a while longer you will see that you catch more flies with honey rather than vinegar.

Mark H



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Steve Ebels

Howard

You'll find that most of the condensing boilers run exhaust gas temps about 20* above return water temps. This is what I have observed on Munchies & Vito's. The ability of the system designer to keep the return temp low and the ability of the boiler to work within that parameter is what seperates the men from the boys. On the boiler side of the equation, Viessman really shines with the capabilty of their variable speed pump to modulate the water flow to optimum rates for efficiency.

Just my two cents.

tombig

Efficiency

Well spoken as always, Steve. That's the point I was trying to make. At higher return temps it might not be condensing but it's still efficient. I heard about variable speed thrugh the Viess. but hadn't really assimilated til now. Logically combined with modulation and that one impressive efficiency machine through all temps.

Tom Goebig

Matt Connolly

Mark, we can agree..

about the importance of challenging that mentality. The cast iron world we live has been around about 30 years too long. The reason I asked about the second hx was from your post:
"Munchkin is rated at 92%AFUE and that is well above the recognized condensing point. What folks don't realize is that there is a two stage heat exchanger in the Munchkin. Single stage units (like the MZ?) will not condense at 180 but munchie will.
That's all. I'm not trying to be antagonistic, just accurate. God bless our troops.

Matt

Mark Hunt

It's NOT the boiler


and increasing the size of the indirect tank will not help either.

Post some pics here if you can. Sounds like something else is up.

Mark H

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john wood

YES IT DOES

Munchkin has two heat exchangers! One primary and one secondary. Look closely at some of the ghost views in the literature. The secondary is where the bulk of the condensation occurs.

James_2

Munchkin

The Munchkin in heating mode with the 925 board takes 5-6 minutes to modulate up to high fire. Your plumber may need a wire kit for the boiler to get an immediate high fire mode for domestic hot water. Piping could also play a part in your problem. Installing a Vision - 1 package might be an option. I would always install an anti-scald valve on an indirect heater. This extends the amount of water available and protects your loved ones from being injured by high water temperatures. Can't put a price on hurting someone you love.

Mark Hunt

Show me (NM)






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