Our first Munchkin Install

Alan(CaliforniaRadiant)Forbes

Sorry, I'm a bit slow.

If word gets around about your high efficiency Munchkins and indirect hot water, you might have more work than you can handle.

By the way, it looks like the house has some type of convector (radiators, BB, etc.); how are you planning on getting return water temperatures low enough for the boiler to condense?

Best wishes,

Alan

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Larry_7

140 MBH in 1920's 2-story, about 2,000 sq. ft. This has got to be one of the the slickest little machines I've ever seen. Cust had old oil to gas conversion boiler common vented into an unlined masonry flue with a standard water heater. HO plans to re-line flue and install a huge wood stove. We roughed in for an indirect for when the existing water heater is disconnected from the flue. See if photo comes through. First pic post. Sorry it's so big. Comments/criticism welcome.

Larry

antman

Y-strainer?

> 140 MBH in 1920's 2-story, about 2,000 sq. ft.

> This has got to be one of the the slickest little

> machines I've ever seen. Cust had old oil to gas

> conversion boiler common vented into an unlined

> masonry flue with a standard water heater. HO

> plans to re-line flue and install a huge wood

> stove. We roughed in for an indirect for when the

> existing water heater is disconnected from the

> flue. See if photo comes through. First pic post.

> Sorry it's so big. Comments/criticism

> welcome.

>

> Larry





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antman

Y-strainer?

Larry, Is that a y-strainer that you have upstream of circulator?
Just curious, Nice neat job!

Ant

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Larry_7

Indeed it is

It's rcommended but not required by the manuf. Thought it might not be a bad idea as this was a pretty old gravity system and the Munchkins's passages are narrow. The added cost of the strainer was minimal.

Larry

antman

Do you feel the sediment this catches, will remain in the strainer assembly once the circulator shuts off? What about cleaning it? Not critisizing, just pickin' the brain.

Ant

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Larry_7

I would say yes

Because the strainer is on the return, I think any trapped stuff would stay there. Cleaning shouldn't be too bad as isolation valves and an air purge arrangement are nearby. The purge valve is visible near the tank. supp and ret valves are this side of it.

Larry

Alan(CaliforniaRadiant)Forbes

Strainer on Return

That must mean the pump is on the return as well (see how sharp I am this morning).

It's not a good idea to place a circulator on the return, for "pumping away" reasons as well as for the reason that you may get a diagnostic failure on the Munchkin. Since you are pumping towards the expansion tank, the differential pressure created by your circulator will be subtracted on the suction side of the pump which will drop the pressure on the system and may reach back far enough to drop the pressure at the boiler which could open the pressure switch and cause the diagnostic light on the circuit board to flash 8 times.

How do I know? Well, let's just say that I learned from first-hand experience.

You can see on the attached picture that the circulator is mounted a bit differently than yours; it's on the supply, but it's pumping towards the expansion tank - it's a bit difficult to see that. The Munchkin would shut down on 8 lights until I moved the circulator to pump away from the X-tank and then all was fine.

Maybe you'll be lucky and all will be fine; you can also raise the water pressure to hide the condition, but it's good to know for the next time.

All the best,

Alan
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Larry_7

Trying two more pics...

The circ is on the supply, pumping away from the tank. The strainer is on the return, before inlet to boiler. Am I missing something here? Do tell. We mounted the gauge on the supply. On cold start, circ pulls press. below 10 PSI but since press. switch remains closed, leads me to believe the press on the return side and in the HX is adequate to satisfy the switch. It would be interesting to see the press. on the return side. The HX apparently has a sizable press drop through it.

Larry_7

Two more pics...

The circ is on the supply, downstream of the tank. The strainer is on the return, before inlet to boiler. Am I missing something here? Do tell.

hr

Flow restricting devices

should never be used on the inlet side of circulators. Y strainers, flow checks, etc can induce cavitation, especially on a high head circulator. It doesn't take much to cavitate a high rpm high head circ. A small amount of debris in that strainer could cause cavatation and low, or no flow, through the boiler.

I understand your concern, however about the condition of the old piping. I'd run a good hydronic cleaner in the system for a few days and flush it good. I'd then put in a good hydronic inhibitor to protect all the clean steel and iron components. Maybe remove the strainer basket after a days running.


hot rod

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Jim_22

Is it possible Antman is mistaking the check valve after the circulator for a strainer?

JIM F.

> Is it possible Antman is mistaking the check

> valve after the circulator for a strainer?



> Is it possible Antman is mistaking the check

> valve after the circulator for a strainer?



GOING TO REPLY ON THE SAME SUBJECT,ANT you should have a flow check after cic

JIM F.

GOING TO REPLY ON THE SAME SUBJECT,ANT you should have a flow check after cic

Larry_7

Sorry for the confusion

I misread earlier post about the strainer. The swing-check is immediately downstream of the circ and is for prevention of flow to the house when the future indirect calls for heat. My apologies for allowing the snowball effect.

Any other possible problems noted? To my knowledge, this is one of the first Munchkins in our area. If I have any influence, it won't be the last. Also, residential indirect water heating is an unheard of twist here. Back in the '60's tankless was all the rage. That set-up died out as the coils began failing or fouling. Those who had them weren't impressed. That may be the reason we are slow to embrace indirects. Heating domestic water at around 92% efficiency is hard to argue with.

Thanks,

Larry

antman

my bad!

Yes Jim, that was my problem, now i got it.
Ant

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antman

my bad!

Yes Jim, that was my problem, now i got it.
Ant

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Boilerpro

Concern about check valve and big pump

The check valve should prevent flow when Dhw pump is running, but how about when that pump is off? What is to prevent gravity flow through the boiler..especially during the summer? Or is this not a real concern due to its low mass/water content. Also, do the Munchkins really need that big of a pump.....Must be a very high head design! I am afraid what you are saving on gas is going to be spent on all the electricity to run that big pump. Just wondering.

Boilerpro

Larry_7

Alan and Boilerpro

The Rep made the pump choice. We're learning on the fly here. Maybe they've had problems with adequate flow. Recommended flow is 1 GPM per 10,000 BTU input. He held our hand more than a little. We did have to throttle the flow back some. I suspect the flame modulation may help maintain condensing temp? The limit is capable of 210* max, although we're set for around 155. See if this addresses the gravity flow issue... the future indirect(with priority) will have a check also. The house circ will cease to be connected to the onboard circ relay on the boiler when the indirect is installed. Individual relays will power the circs and an isolation relay will simply connect T T on the boiler to bring on the burner. Unless the house circ is running, there should be no flow to the house. Am I making any sense? Man, it's late. Sorry I have as many questions about this thing as answers, if not more. Sure is slick, though. Keep hammering me. I'm hungry for info. One other thing...anybody had slight gas odor problems from the vent on ignition and/or extinction? We're using Nat. gas (sidewall concentric vent). Hoping to avoid nuisance odor complaints to the utility when the neighbors walk the dog.

Thanks

Larry