Alan Forbes & ME - RE: Munch pumping away

Dave Yates (PAH)

I didn't argue the point yesterday because I didn't have the instruction booklet with me. Perhaps you've both had west coast instructions, but my east coast installation instructions specifically say to install the pump on the system supply side. (pg# 8) The written instructions also request the air vent be installed on the system return (pg# 8), but the drawing (pg# 9) clearly shows it is to be installed on the system supply just ahead of the expansion tank. However, the air eliminator we used has a bottom tapping for the expansion tank Dealers choice!

Not sure why they want the PRV water feeder on the return piping, so we continue to connect ours at the PONPC.

There are no drawings showing completed connections and no mention of P/S. However, it was my choice to use P/S with the pump indicated to ensure proper flow through the boiler. I don't want velocity noises out in the system or the possibility of reducing flow rates below the heat exchanger's needs. Perhaps this goes back to my GC days!

We do have a Y-strainer ahead of the boiler on the return. That's something I wanted to protect the HX from any floaters that might migrate back from the old system.

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MURPH'

would the.....

ponpc change at all considering there really is no mass here, seems most is done through flow and modulation.. Being that it would not make a difference other than time and cosmetics, could not the expansion tank be connected remotley and what about inverting it so the water would be at the bottom, air at top?? seems that may rid you of some debris issues laying on the bladder..


my two cents


Murph' (SOS)

hot_rod

bladder infections

No bladder infestations cause it's downstream of the strainer. High head at the HX, so the short primary loop doesn't know it's short. Potential exists for the short sharp pressure drop Alan & ME hinted about. Could well be they have newer instructions and have had the benefit of HTP training.

john wood

personally I reccommend

All munchkins on a P/S setup. Pump away from the expansion tank and into the return. Because of higher head thru HX, this lessens the likelyhood of any teakettling or in a low pressure situation, tripping the low water pressure switch. Also place a strainer on EVERY job as it only take a flake of something to obstruct ONE tube in the HX and cause headaches! Take MR. Murphy out of the equation.

[Deleted User]

Do the drawings...

look like they were done by Siggy?

The problem of the pump somes from installs where the expansion tank is on the inlet, and the pump is on the outlet, and the system is run with a high head pump, and the system fill is at a lwo pressure. When the pumps turns on, the pressure switch sees a low pressure condition and locks the boiler out. It's the "droop" zone of the pump and the PONPC. To avoid this potential completely, you can pump away from the PONPC and towards the boiler. This way the boiler will always see the positive head of the pump and avoid nuisance drop outs due to low pressure.

Come to think of it, I'm not positive that it is reflected in their installation manuals, it may just be something I was told by one of the factory guys, but I suspect that if its not in their current install manual, it will be on next printing.

Sorry for any cornfusion...

In your case, with it being a P/S design, it probably won't cause any nuisance problems for you.

ME

Dave Yates (PAH)

Don't look

like anything I've seen from Siggy. I'd be leery of having multiple zones without P/S where a high head HX exists. An 011 on a 3/4" baseboard loop will typically give off enough noise to be noticable at 2 AM - right when I'd like to not have the answering service call(G).

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Alan(CaliforniaRadiant)Forbes

Vision I

The drawings in the new instructions look like they were done by Siggy and they all show:

1) primary-secondary piping

2) Circulator on the return

3) Something new: A secondary manifold; the individual zones pull off this manifold. No pump on this manifold since it's a manifold and not a loop.

Guess what? The air eliminator and expansion tank are on the secondary manifold and not on the primary loop.



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Unknown

Vision I

drawingsa were done by Siggy. Heat Transfer Products I believe had him do them for the new books and manuals. They attempted to cover every possible situation for installation.

I think the next thing they are having him do are the wiring diagrams.

Colin

I call it modified..........

p/s and have been doing it for about 7 yrs. now with great success. It really makes the Munchkin shine as loads are shed or micro loads started the reverse flow between the closely spaced tees does wonderful blending and the almost immediate warm return water to the Munchkin causes it to modulate to low fire.

Aint it Fun!
Colin