Connect new munchkin to 50 yr old water expansion tank

Robert_22

I'll attach pictures of the system for you to see the primary secondary loop and the old water expansion tank, as well as anything else you want to comment on.

My contractor wasn't the lowest quote. I'm paying him $10,700 to replace my old system with a new system. His quote was competitive with the others, and he was the most respectful and responsive. Whenever, I called him he would either answer the phone or call me within 20 minutes. He was referred to me by my brother-in-law.

I regret hiring him now due to the way things turned out. I went four days in 20 degree weather without any heat or hot water plus. He tried to get me to hiring an electrician separately. He has a gas pipe fitter permit , but doesn't have a plumber's license. (He lied about his qualifications; I asked him about pulling the electrical, plumbing, and gas permits up front. Most importantly, I'm afraid that the 80,000 BTU system is two small for my two story victorian home.

Some of the pictures should be rotated for your viewing.

Robert_22

Connect new munchkin to 50 year old water expansion tank

Is it okay to connect my new munchkin water boiler (vented system) to my 50 something year old water expansion tank? The munchkin boiler manual calls for a diaphragm expansion tank with an automatic air vent on top the air separator to remove residual air from the system. There are no air vents and air separators configured with my new munchkin and old expansion tank connection. I'm no expert, but I don't think my old water expansion tank has any of those features, certainly not a diaphragm. Does my old water tank have those features built into it already? Or, would this configuration cause my munchkin system to eventually fail? Would this configuration disqualify me for my munchkin warranty?

bobbyg_2

You need some way to get air out of the working system and into your tank. I suggest you read page 12-16 to explain why you still need an air separator (only instead of an air vent on top of the air separator - pipe it sloping upward to your tank).

http://www.bellgossett.com/BG-Literature-Detail.asp?LiteratureID=1195

Plumb Bob

I can't comment on your Munchkin warranty question, but the instructions given are just common sense.

I mean, if you buy a car and it says "Don't drive it around with the parking brake on", the normal response is not "Why can't I do that if I want to? Will it void the warranty?", but "Yes, of course, that's obvious".

Putting in a new expensive boiler, but not putting in a relatively cheap air separator and modern (diaphragm) tank is not smart.

Robert_22

Homeowner Response

Thanks for the two responses. My plumber doesn't want to replace my old steel expansion tank, and I was trying to talk him into replacing it. According to pages 12-16 that you sent me, it sounds like my expasion tank will be sufficient as long as it has the features described on the manual you sent me. I wish there was a way for me to further investigate the features of my five decade old water expansion tank.

I also thought that I would have more leverage if I could argue about the warranty. I have the question out to Heat Transfer Products, and I'm waiting for a reply.

Thanks

bobbyg_2

If the air isn't properly taken care of, the air will naturally collect somewhere in your system and will eventually cause the system to become "air bound" meaning the circulator probably won't be able to move water past this point.

Which means you won't get any heat to this area. If enough area can't get the heat, then your boiler won't run much because the water will stay hot, because there will be no water movement to "lose" the heat.

Any "good" hydronic heating system has to address air properly by one of two ways:

1. capturing the air (air separator and auto air vent) and relieving it to the atmosphere (using a diaphragm tank to take care of expansion)

2. some way of catching air when it separates (in old cast-iron boilers - the boiler itself was an "air separator" with a pipe coming out of it and going into the old steel expansion tank) If you are removing this "air separator/boiler" then you must put in some other method of separating air (air separator) and instead of a auto air vent, pipe this "captured" air so that it can travel to the steel tank....that air in the steel tank allows the tank to absorb the expansion in the system.

Hope this helps.

Paul Pollets

Robert...

Sometimes we must take action to ensure that the replacement has everthing going for it. To leave the existing steel tank and not replace it with a diaphragm-type pre-charged tank is like not wiping your nose after you sneeze. Or perhaps not changing your underwear for 3 days to save a little on the laundry bill. Not yours, your plumber's.

Just do it!!!!! Anything less doesn't make sense and is considered less than thorough craftsmanship.

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scrook_2

Spend the $100 (give or take) for a bladder x-tank and fittings and just do it!

Robert_22

Plumber refuses to do it

I've addressed this with my plumber several times. He refuses to remove the old steel expansion tank, because 1) he didn't include it in the contract, and 2) he says the old steel tanks is adequate. Should I just pay him and then hire someone else to later add the diaphragm expansion tank with the air separator and air vent?

Steamhead (in transit)

Diaphragm or bladder tanks

are certainly a newer design. But are they better?

Keep in mind that the diaphragm or bladder is a moving part. It will eventually fail. Your present plain steel tank has lasted so long because it has no moving parts.

As long as you have a good air separator, piped in a Pumping Away setup, connected to the tank by a B&G Airtrol fitting on the tank, you should be OK. This setup has no moving parts and should last a long time.

I believe this is what Dan has in his own house- he mentioned it in one of his books.

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Plumb Bob

I'm not one to complain when people pick the lowest quote, it's natural to want to save money, but in this case you may be paying for having chosen the lowest quote. It sounds like this guy has no standards.

Yes, you should pay more if needed to get a new tank and air separator.

Now what I am more worried about is if this guy did a hack job of the rest of the installation. Munchkin installation is not for amateurs. Do you have primary/secondary pumping? Are you pumping away from the expansion tank? Do you have outdoor reset installed and the curve properly set? Can you post some pictures?

Paul Pollets

Quality Control

I'd make sure the contractor has installed the Vision 1 control on the Munchkin, than fire his sorry a*s and find a hydronics pro that understands why expansion tanks are changed when the boiler is replaced. I'm puzzled why the contractor didn't provide a price for replacement when asked????

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Robert_22

My pictures

Mike T., Swampeast MO

Motion seconded.

Paul Pollets

Sorrry...

Robert, your system has piping errors. The author of this site (Mr. Holohan) has provided pipe sketches and articles on gravity conversions in his web library and in his books. I wish I had more time for 'forensic analysis", but it's heating season and my time is scarce.


Hopefully you're in a major city where you'd find someone who has done more than one gravity conversion changeout.




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Mark Hunt_3

Please keep in mind


that these old steel expansion tanks were not connected to systems that had external air removal systems. The air was supposed to go to these tanks. Even then, those tanks became water logged at some point and required draining.

Attach ANY "modern" air elimination device and that steel tank just gained an enemy. Diffusion. The more you take out, the more that needs to be replaced. Nature hates a vacuum.

That "air pocket" will be absorbed VERY quickly.

Went on a sales call a few years back to a home that needed a new boiler. The reason they needed a new boiler was because the existing one was smashed by a steel expansion tank that had become water logged. The original expansion tank was not replaced when the home was changed from a gravity system to a circulated system and an air scoop was added to the system.

Lady of the house just finished her work out on exercise equipment that was located next to the boiler. She walks 15' away and SLAM!!!!! The 80 gallon tank became water logged and the weight caused the joist to split. The tank swung down and took out the boiler. She would have been killed had she exercised a minute longer.

Modernize everything.

Mark H

Steamhead (in transit)

Unfortunately

I've seen plenty of waterlogged diaphragm/bladder tanks too. If this is caused by a ruptured diaphragm/bladder, the tank needs to be replaced. And we can't always depend on "transfer houses" to have them in stock when needed.

In the case of the fallen tank you cited, I'd go after whoever didn't support it properly.

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Mark Hunt_3

Well


the guy that installed that tank is probably dead since the system was installed in the early 1930's.

It was supported well enough to last as long as it did, thickest strapping I have ever seen. The floor joist split.

No-one ever explained the required maintenance to this young couple and they never drained the tank. They did not know they were supposed to and apparently neither did the techs that serviced the boiler.

Mark H

Al Roethlisberger

I like expansion tanks - no parts to wear out


Agreed, sounds like an unfortunate "user error" versus design flaw. Although I guess one could argue that the supporting infra(joist) could/should have been built out for "worst case" =P

I'm just a DIY'er that is new to this game, but for all my reading, I have really become a fan of old expansion tanks due to their simplicity and long-term durability.

If the tank is in good shape, I don't see why you can't use it. I'd just make sure you(or your installer) knows how to properly install it so that it can operate properly.

Mark Hunt_3

They work


no issue there.

But as I said, if you attach a modern air elimination device you can expect to have to drain the tank more often. The more air you remove from the system, the faster the air in the tank will be reabsorbed back into the system. Even on the older systems with no other air elimination than the bleeders at the radiators, that air in the tank gets reabsorbed back into the system water and they needed to be drained from time to time.

I just want folks that are browsing here to understand what happens with these tanks. They need to be drained occasionally and with a modern air eliminator in the system they will have to be drained more often.

Mark H

Unknown

Sorry Mark,

"if you attach a modern air elimination device you can expect to have to drain the tank more often. The more air you remove from the system, the faster the air in the tank will be reabsorbed back into the system."

But I disagree, if the tank has a B&G Airtrol(as Frank mentioned), proper air-scoop, pump location, and piping to the tank, any air that does find its way into the system, would be separated right back into the tank would it not?

Dave

Mark Hunt_3

Well

think about for a second.

Where is there a ready air source? The scoop or micro-bubble will vent the air to the atmosphere and the air in the tank will be reabsorbed and then it will be removed by the air eliminator. That air pocket in the tank will diffuse back into the system water faster than air outside the system piping would. No?

Keep in mind that those old gravity systems had no automatic air removal devices on them and the tanks still became water logged eventually.

Now we add a circulator that moves the water MUCH faster than it ever moved in the gravity system and we get turbulent flow past the B&G Airtrol connection and the scoop removes the air that came out of solution.

The B&G literature shows the Airtrol tied into a B&G air separator so that any air removed goes back into the tank. The Airtrol MUST be used with a B&G air eliminator. Vent that air to the atmosphere and you will have a water logged tank relatively quickly.

Mark H

Plumb Bob

THAT'S NOT FAIR!!!!

It's cruel to tell the the OP the piping is wrong, but then refuse to tell him why. I'm not an expert and can't figure it out myself, or I would. Maybe someone else here can help out?

To the OP; did he install outdoor reset? This is where it uses an outdoor temperature sensor to control the water temperature, so the water is always only as hot as it needs to be. The pump will run almost all the time. If you don't have it, you're losing the most important benefit (comfort) of a condensing boiler.

Gordy

Airtrol

Mark, the Airtrol tank fitting lets the air in the system go back into the expansion tank. But it does not allow the oxygen saturated water in the expansion tank to migrate back into the system.

My WM boiler has a built in air removal tapping next to the supply, so my ATF is piped direct off of this to the compression tank. no need for an air seperator in my situation.


If the water supply to the auto feeder is off once the system pressure is set, I don't understand how the tank can get water logged.

DanHolohan

The plain steel tank in our house

has been here since 1950. I like it because we're the same age. I have a B&G Airtrol tank fitting on it and we never need to drain it. We've been in the house for 30 years.

.._2

..

Mark Hunt_3

Well

it is not piped P/S as per HTP's instructions.

I see four pumps and only two check valves. (I can't tell if those are IFC's or not) If those are not IFC pumps, there are going to be some wild flow issues and once the heating season really kicks in the domestic water is going to get VERY hot.

I hope the installer did a combustion analysis.

Mark H

Plumb Bob

The OP has stopped posting but I hope he checks this thread. A Munchkin without P/S is a potential disaster. This was done by someone who only knows cast-iron boilers.

I bet he didn't put in outdoor reset either, not just because he is maximizing his profit but because he doesn't really know what outdoor reset is.

Paul Pollets

No Offense, but

In all fairness, when I have the time, I gladly share the technical. When I don't, I don't. I recommended the owner find a pro. Even if I described in detail the piping errors, only a pro could fix it. Many problems discussed on this site were caused by poorly trained contractors or homeowners who got in too deep. The internet is great for sharing knowledge, but there are limitations in both a possible explanation for why a system is problematic and the 'fix'. ...and suppose the owner is a lawyer? There could be liability for diagnostics or critique. I'm careful about proscribing a "fix" over the internet.

BTW, I usually get paid for my forensic troubleshooting experience. It's my business. My customers have told me they often visit this site.

There's always some 'lurking' on this site who's willing to detail the problems. And have the time to share details.....as you can see.

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Mike T., Swampeast MO

I cannot agree Mark, at least as pertains to gravity conversions.

It's sometimes easy to forget that the whole point of "Pumping Away" is about what happens on either side of the point of no pressure change, e.g. the point where the compression tank connects to the system.

Even Dan says in Pumping Away that such circulator position really doesn't matter in many older systems. I'm assuming a bit here, but I believe he had original gravity systems as they were never designed for forced circulation.

As long as the converted gravity system is essentially unmolested (meaning any changes made were piped in the ways of the dead men) it's genuinely impossible for the circulator to create enough differential pressure to even come CLOSE to producing sub-atmospheric pressure on the suction side when pumping TOWARDS the point of no pressure change.

Never forget that no circlating pump--no matter how large--cannot move a single molecule of water into or out of the expansion tank and its associated piping. The point of no pressure change guarantees this.

One and only one thing CAN allow water to circulate from the system past the point of no pressure change into the expansion tank and piping: GRAVITY The cool water in the tank can fall into the system to be replaced by the hot water produced by the boiler but such circulation is COMPLETELY SEPARATE from the circulation induced by the circulator!

Converted gravity systems are not immune to gravity-induced air problems. The air in the tank CAN migrate to the radiators. Bleed the air from the rads and you will eventually wind up with a waterlogged tank when you add water to maintain the proper system pressure.

The Bell & Gosset Air-Trol fitting stops this gravity-induced circulator before it can ever occur. Such is the ONLY thing the Air-Trol can do, and it does it VERY well! You do though have to properly cut both the inner and outer tubes per instruction to suit the height [diameter] of the tank.

Yes, the Air-Trol instruction DO show it attached to an air separator but this is not essential--it's merely a convenience as it sends the "extra" air in the initial fill water directly into the tank; otherwise it will just collect at the top of certain rads in the system and if my experience is any measure it will always be the exact same radiators. Release that air in the rads by venting and you must replace with a small amount of water. If that water comes from the compression tank, the static pressure in the system will fall and you'll have to add more water; if replaced by an auto-fill valve you'll never know it happened... That "plain" compression equipped with the B&G Air-Trol tank WILL NOT WATERLOG even if it's not connected to the "output" of an air separator!!!!

Gordy

Exactly Mike!

Excellent explaination !

Gordy

Mark Hunt_3

You are correct


I was wrong about the Airtrol fitting.

Take another look at the OP's pictures and you will see no Airtrol fitting however.

I would amend my comments to say that if a steel tank is used, an Airtrol fitting MUST be used.

I can tell you that I have rarely seen them on steel tanks in this neck-o-the-woods though.

Mark H

Robert_22

Home Owner Responds

I thank everyone for the input. I just want an expert to tell me what is wrong with my system.

I am just an engineer, who got four estimates and hired a guy that I thought was the best. He started working on 12/1/07, and he is still not done. I went 4 days without heat and hot water, while temperatures during the day in Boston were 20 degrees Farenheit. I read the munchkin manual, and pointed out things that my contractor did not do. For example, he didn't implement the primary secondary loop until after I circled the page in the munchkin specification for him. He implemented the loop, but I do not know if it is done correctly, because it looks a lot different that the one in the manual.

Our house does not warm up uniformally, and we periodically get ice cold showers. I know there are still problems with the installation, but I don't know what they are. I can read the manual, but I have trouble correlating what I see in the manual with what I see with the installation. For example, it looks to me as if the the return line for the second floor zone goes into the feed line for the second floor zone, but I could be wrong.

I don't think the Contractor is maicious; I think the Contractor just doesn't know what he is doing. It is pretty obvious to me.

If I could point out to him his errors, I'm sure he would fix them for me, although I would have to convince him that I am right.

A simple list of what is wrong would be a great help. A brief supplementary statement explaining why it is wrong and the impact on the system would help me convince him.

I'd also be willing to hire an expert in the Boston region. One of the previous responders wrote that he does this for a living. I'd be willing to hire him if he can come check it out. How do I know where you are located.
Thanks again
Bob

Mike T., Swampeast MO

My Air-Trol is the only one I've seen in my neck of the woods as well...

I trusted Dan even if I didn't completely understand when I first read How Come and Pumping Away...

The Air-Trol ain't free but it will cost FAR less than either the single huge diaphragm tank (or BANK of smaller tanks) required to replace and considering how well those old tanks were built, even the old ones may well last longer than the "modern" diaphragm tanks. And they will CERTAINLY last FAR longer than a stressed-out, undersized diaphragm tank that [seems] to be the common replacement.

A nicely curious homeowner recently asked if a #30 Extrol was equivalent to a 30-gallon plain tank. Search to find my answer...

R. Kalia_10

Have you tried "Find a Professional" under "Resources"?

Mike T., Swampeast MO

Wonderfully stated Paul!

Just the time you spent examining those photos was likely worth more than the value of that installation!

Mod-cons (including Munchkins) CAN be installed without primary-secondary but that is FAR, FAR, FAR, FAR from the way it can be done!!!!!!!!!!!!!

Plumb Bob

If you are an engineer, P/S piping may be a new concept but you should be able to understand it. I don't know if you have a newer Munchkin manual, but in my 4-year-old copy, the first two piping diagrams are wrong. You have to go to one that shows closely-spaced tees. These are essential.

For an explanation see

http://www.radiantcompany.com/heatsources/primarysecondary.shtml

(don't worry about the "open system variation" described on that page)

I know it looks strange and unnecessarily complicated but it is necessary. There is one pump for the boiler loop, it drives water through the boiler, through the closely-spaced tees, and back to the boiler. It doesn't send any hot water to any of the zones. Then you have a pump for each zone, it drives water through the closely-spaced tees and through the zone, but it doesn't send any water through the boiler.

There is more to this but those are the basics. The section between the tees must be very short (obviously). This is the only section that is common to the boiler loop and the zone loops. This creates a zero-head "water source" for the zones and thus makes them independent of each other.

Any time a zone calls for heat, both the boiler loop pump and the pump for that zone must run. Consider the indirect to be just another zone for piping purposes (but electrically it is a special zone because it has priority).

You say you have P/S piping but I don't see those closely-spaced tees. It appears to be piped like a cast-iron boiler where the zones are parallel to each other but the boiler is in series with the zones.

Robert_22

Homeowner responds

Thanks again, Kalia and J. C. Both of you pointed me to information which will be very helpful. I am working in Reston, VA today, and I'll be flying home tonight. I'll start educating myself more with the materials that you pointed me to. I know it will help. I do have the manuals for the munchkin and the superstor, but I'veonly been reading the munchkin manual. I'll have to check the version number.

I also think there is no vacuum valve on the superstor, no flow check on the first floor zone, no backflow preventor. Am I correct?

Thanks again.
Bob