[RE-wrenches] Magnum MS4448AE Compatibility Question

[Allan Sindelar]

Wrenches,
Thank you to you Wrenches who have responded. Keep them coming; I'm
collating all as part of our customer support on this. We have several ideas
to try out.

Darryl, it's not excessive draw. I had a Kill-a-Watt on the AC input during
on-site testing. I saw a momentary peak of 360W (for all, including AC
pumps). The observed draw sequence was 205W for the purge blower, followed
by 270 for the igniter for about 5 seconds, dropping to 220-230W upon
ignition. Later, the hydronic distributor's rep turned down the sidearm
circulator pump from high to low setting and reduced this pump draw by about
45-50 watts. AC voltage during testing bounced around in the range of
117-123VAC, but the fluctuation was not load-based.

At this point Magnum has stepped up to support us; we'll see where this goes
and how it (hopefully) resolves. Magnum has suggested a 50 microfarad
capacitor, per Peter's suggestion. They have also contacted the wholesale
distributor for Buderus boilers for New Mexico, and I believe the plan is to
ship the boiler to Magnum for testing. I may have further questions for the
list, and I'll eventually post how all this resolves.

Allan at Positive Energy

-----Original Message-----
From: re-wrenches- On Behalf Of Darryl Thayer

Some of the hot surface ignitors I have seen draw a lot of current, in the
order of amps.  I would expect the inverter to drop out if it were
overloaded however.  Also does the magnum drop voltage at very low loads?
Where the furnace controls can not function due to low voltage or poor wave
shape.

Darryl


--- On Wed, 2/11/09, boB Gudgel <boB at midnitesolar.com> wrote:

>> Peter Parrish wrote:
> > 
> > As an old Ham Radio Operator, it would seem the
> solution is very simple. First, I assume that the voltage is
> compliant and so is the frequency. The problem is high
> frequency noise (hash from the switching circuitry) on the
> waveform that has not been filtered out. Figure out the
> switching frequency and get a low-pass filter whose cutoff
> is below the switching frequency but above 60 Hz. Make sure
> the filter is rated for the load, but since we're taking
> about a burner control/igniter, we're talking low-power,
> correct? LPFs are low-cost commodity items, probably in
> DigiKey or similar catalogs.
> > 
> > - Peter
> > 
> 
> This may be true about high frequency switching interfering
> with something, but I believe the problem with this ignitor
> is that it is a very poor design. Judging by what I read on
> their company forum, it doesn't look like they have a
> clue about
> this problem. Maybe you can go inside the Buderus and
> filter something there or maybe you can fine another product
> to try ?
> 
> boB
>
*From:* *David Katz
>> > 
> > Hi Allan,
> > This is not an unusual problem. i have seen it with
> conventional forced air heating systems. The burner controls
> would not run on A Xantrex or Outback sine wave inverter.
> There is something about waveforms from inverters designed
> by Trace legacy engineers. I had to put in Exeltech or
> Studer inverters to operate the heating control system. you
> can do this and still run larger pumps and fans on the
> Magnum.
> > David