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Axiom DMF150 ?

Dave Carpentier
Dave Carpentier Member Posts: 172
Anyone using one of these ?
Seems like I could avoid placing a makeup water line, a prv, backflow.
I could fill my system (without using my well water), add chems, monitor loss visually and with its NO/NC alarm contacts (Hook it up to my "Aux limit" on the boiler and it would even shut the boiler down).
The price is up there, but its tempting..
30+ yrs in telecom outside plant.
Currently in building maintenance.

Comments

  • Tom_133
    Tom_133 Member Posts: 820
    I have used many on systems that need glycol, and they work perfectly. Longevity, not 100% but they are simple and easy to repair. Not saying they dont last, just dont have a long enough track record.
    Tom
    Montpelier Vt
  • mattmia2
    mattmia2 Member Posts: 5,512
    It is an option although probably not wort the added cost, complexity, and reduced reliability unless the water is really bad. Some people put a water meter on the feed. You have to be careful that it can read the tiny flow that the makeup water will have.
  • hot_rod
    hot_rod Member Posts: 16,288
    Most importantly you fill and clean systems, then add good  water for final fill.
    check for hardness, TDS, chlorides as per the installation manual water spec. With small tight systems, they should not need water addeded after fill and a few days running

    An extra expansion tank as a PIG is another option to a fill valve of fill system. Charge the tank to 60 psi with fill water, add a Caleffi Autofill set at 12 psi. This gives you 3 gallons or so if extra fill water for the cost of an extra tank and Webstone valve.
    Most new boilers have low pressure or low water protection built in.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    GGross
  • G Averill_2
    G Averill_2 Member Posts: 48
    We sell quite a few of them, and the larger model DMF300. We have one in our newer radiant system in our corporate office warehouse too. All of our snowmelt systems will have one of an appropriate size.
    They will require a replacement part from time to time but overall are a reasonable value.
    GGross
  • Dave Carpentier
    Dave Carpentier Member Posts: 172
    edited June 7
    hot_rod said:

    An extra expansion tank as a PIG is another option to a fill valve of fill system. Charge the tank to 60 psi with fill water, add a Caleffi Autofill set at 12 psi. This gives you 3 gallons or so if extra fill water for the cost of an extra tank and Webstone valve.

    Cool idea. Do I have the thinking right here ? HGT30 tank, a webstone with the drain(/fill) and a liquid gauge (0-100 or such) between the webstone and the tank, open valve, bring the air side up to 60# , add water from a clean (city water ?) source that has a higher pressure, stop filling when the airside pressure starts to climb, then connect that to the autofill, and onto the system ?

    I guess I couldnt monitor for loss via the tank's liquid pressure, since it should stay at 60# until empty(ish) ? Put an air gauge on the other end ? (can you actually remove those airvalves or are they stuck in there with permanent locktite/etc ?)

    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • mattmia2
    mattmia2 Member Posts: 5,512
    The air adjustment valve is usually a schrader welded to the tank.
  • Zman
    Zman Member Posts: 7,330
    Those are great products for glycol and systems with no water on site. I like it better than giving the system free access to make up water because you sometimes never know you have a leak. The new model you are looking at with the alarm would be nice for second homes. Those dry contacts are easy to integrate into the home security system, just like the newer mod-cons.

    I have a commercial client that had a large glycol feeder that was not working. The maintenance staff bypassed the feeder to keep the system full by connecting it to the building water (they did use PRV and RPZ). Over the course of 6 months or so, slow leaks in the system caused the fill water to dilute the glycol to 9%. It is a system with rooftop units that require 30% glycol. In this case, the system volume is > 3,000 gallons. With glycol prices over $30/gal, this was a very expensive mistake.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Dave Carpentier
    Dave Carpentier Member Posts: 172
    So you can actually fill a system with one of these things ? Im planning on flushing and then trying to blow out my 1/2" wirsbo zones so that I can start fresh. Not sure how many gallons, but about 1500ft of 1/2" plus a 16 gal buffer tank plus the boiler and near pipes.
    The docs for the DMF150 say it flows 1gpm at "free flow". I wonder how much it slows down as it makes its way to 12psi ?
    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • Zman
    Zman Member Posts: 7,330
    I would be concerned that the pump is not designed for long duty cycles. If have used it to top off after partial drain downs, never to fill the system. You might be OK if you run it for 5 or 10 minutes then let it rest.

    As far as the power purge goes, I would set the system up with traditional boiler drain purge points so you can power flush the system with a hose or use a transfer pump to add glycol.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    GGross
  • Captain
    Captain Member Posts: 26
    IMO if you consider the cost of a fill valve, additional expansion tank, pressure gauge, valves, etc. Then your better off with the DMF150. The DMF150 comes with a wall bracket, precise digital pressure display and setting. Not to mention the translucent storage/mixing tank that lets you know exactly how much fluid the system is taking. N.O. or N.C. dry alarm contact and red LED alarm light. Alarm settings for high pressure, low pressure and low tank fluid level. Plus fluid that is drained for service or system mods can simply be poured back into the tank. DMF150 is a no brainer on any system, especially glycol systems
  • hot_rod
    hot_rod Member Posts: 16,288
    You want 5 fps velocity to adequately purge air and any heavy debris from a system. So determine the largest pipe size, use the tables at engineeringtoolbox.com to see what gpm is required in various tube size to get adequate velocity. 

    1 gpm may be enough for a single 1/2” Pex loop, more like 10 gpm or higher for 1” or 1-1/4”copper tube
     I think the weak link in pumped fill tanks is the small RV style pump, they tend to be seized up when not used for a period of time. Good to have a pressure alarm connected to alert you that they are not pressurizing.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Dave Carpentier
    Dave Carpentier Member Posts: 172
    If I found the right table, PE pipes, it shows 5fps = 4.8gpm for 1/2".
    My Alpha2 can do 13ft of head at that flow, but the table shows 65ft length = 13ft of head (20ft head per 100ft of 1/2" at 5 fps)

    So the DMF combined with my Alpha circ is unsuitable for in-floor filling, at least as far as pushing the air out. It could potentially fill the boiler/buffer/nearpipes in my setup (a few gallons at a time to let the motor rest would be prudent). This area could just self-vent with some local sectioned-off circulating past the autovents.

    I havent discounted it completely, it's still a cool device to monitor and recycle through.


    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • hot_rod
    hot_rod Member Posts: 16,288
    You can fill and flush with a garden hose connected to your hose bib or any connection. That will get you some good flow rates. Stay below the boiler relief pressure by a few psi.
    An inexpensive plastic sump pump from the box stores will get you some good flow rate, and not too much pressure to trip relief valves.

    For large pipe systems and geo loop fields a some folks use a 1 hp pool pump and a plastic trash can for quick and easy high flow pump cart. You should get 20, 30 gpm or more from a pool or spa pump.

    But unless you have a bunch of solid debris to get out, just fill through the "fast fill" fill valve, purge a section at a time and and let the circulator and air purger and dirtmag do the final cleaning and air removal.

    Running the system up to a high temperature for an hour will also speed up air removal.

    A 3 step process would be.
    Fill the system with whatever water you have on site, add a can of system cleaner and run for a day or so.
    This gets flux, pipe dope, oils cleaned out.

    Drain and flush again with site water to get the detergent out.
    Drain one more time and add good water, demineralized, DI,RO water. When it is up and running, air free and quiet, add a can of hydronic conditioner to protect all the cleaned surfaces. Rhomar, Fernox have a 2 can aerosol kit for cleaning and condition hydronics, squirt it in at a hose connection.

    Feeders are nice for glycol systems where they cannot be connected to potable water.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 7,330
    Flushing, filling, and maintaining pressure, are separate conversations. Leave yourself boiler drain purge points to flush and fill, flush with high pressure from a hose hooked to domestic, fill glycol with a transfer pump and maintain with a feeder.

    You can probably fill with the feeder if you go slow and take some breaks.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein