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Dan, Long-winded response compendium below. This is my record of a on-list and off-list Wrenches discussion of a similar boiler issue on one of our jobs, about a year ago. The issue never got resolved with Magnum or Buderus, but when the customer's hydronic contractor changed to a different boiler the problem disappeared and hasn't returned. Below the thread is my email to Buderus, with a reply from engineering acknowledging the problem. This isn't Munchkin, but you might find some material here to use in your situation. Allan Sindelar
Renewable Energy Wrenches Forum on Magnum
Inverter/Buderus Boiler Incompatibility February 2009 Original Request
Post: Wrenches, We have an unusual
problem,
and I need to know if anyone else has had this or a related problem,
and what
to do about it. This concerns a new
off-grid
residential system, very conventional: 1,800W PV, Midnite E-Panel with
Magnum
MS4448-AE inverter, MX60, 16 S-460s, installed summer 2008. This
existing home
is being extensively remodeled, and the home is not yet occupied. A
local
mechanical contractor installed a new infloor radiant (gypcrete)
hydronic
heating system using a Netherlands-made (German company) Buderus GB142
high-efficiency boiler. The problem is that the boiler won't start
reliably on
the inverter. It appears that the hot-surface igniter does not get full
AC
voltage (it runs on straight 120V AC, but is supplied through the
boiler's
control circuitry). We tested the igniter by disconnecting it and
plugging it
straight into inverter AC and it lit right up. The mechanical
contractor has
tried a replacement Buderus GB142 boiler with the same result. I was
told that
they brought out a generator and it also failed to ignite on generator
AC, but
not knowing the generator used or the way it was wired (I believe an
extension
cord to a portable) I don't put much weight on this data. They also
took a
Lochinvar Boiler to the site to test the theory that a different
manufacturer's
boiler might work. The Lochinvar boiler, which uses a different control
and a
spark ignition rather than a hot surface igniter, worked on site
without any
problems. I'm looking for
solutions.
Magnum tech support had not heard of this. Have you? Also, if indeed we
have an
inverter that is incapable of running this load, how do we make it
right to the
homeowner and the mechanical contractor? What should be Magnum's
obligation?
What should be ours? This issue hasn't come up here since the days when
the
Trace SW mod-sine series was the waveform standard. Thanks, Allan Sindelar,
Positive
Energy, Inc., I have hit this one
a couple
of times but not with the equipment you are listing. It turned out to
be how
the sine wave crossed the X axis and the controls did not like the wave
form. Dana Orzel. Great
Solar
Works, Inc., Followup off-list: From:
Allan Sindelar What
was the incompatible equipment, please? How
was it resolved? Did
the solution involve Magnum's participation? Thanks,
Dana Allan It
was not a Magnum inverter, it was a SW Trace inverter and the controls
were
Johnson controls. It was a forced air system which the PV system was
not sized
to deal with, too much wattage and too long a run time. The contractor
did not
listen to me when I told him it was not a good idea. We ripped out the
forced
air system and installed a hot water baseboard system with Ivan Labs
CID10B24
pumps to circulate the boiler and an old-school standing pilot
Teledyne-Laars
boiler. In
another instance, an oven would not fire up and we installed a Line
Tamer
120input/120output transformer on a spring wound timer to smooth out a
wave form,
It too was a SW Trace inverter. In
yet another instance we used a couple of big capacitors to deal with
the surge
for a high end audio system, using Carver Cube amplifiers [2], to deal
with
bass note pulses that were shutting down the receiver. It also was a SW
Trace
inverter. Dana
Orzel I second Dana's
response. I have observed that the MS4448 waveform quality degenerates
quite rapidly with imbalanced loading of one or the other of the 120
volt
output legs. I can't give a quantitative (% distortion/amps) number to
it, but I would classify it as severe. I first noticed it when doing
some
test measurements in the shop, and found large discrepancies between
various
current metering devices I was using, as some of the meters were not
measuring
RMS, and the distortion was throwing them way off. And when using 120
volt motors, even though their surge may be well within specified load
limits,
count on things not going well. I use a lot of
these Magnum
4448's and have never had any trouble like that. I did have some real
odd
behavior out of the first three I installed and we worked with Magnum
to get a
software upgrade that would handle surge better. Mine where falling off
for a
lengthy period of time when a heavy load would kick on enough so that
things
like clocks would reset and blink. So maybe if you have a low serial
number (sub-150
I think?) that may play a part in it. I will say these aren’t the
Cadillac by
any means but I feel they are a good value for the dollar. Ryan Stankevitz,
Alternative
Energy Systems of Sorry to hear about
your
troubles. Have you tried the trick with an incandescent light bulb? I
know about a remote telecom site powered by SW’s where they had sorts
of
trouble with the gear. Somehow they came across the idea of replacing
one
of the CF’s with an incandescent and no problems since. Don’t ask me
why…I’m just happy to be able to get my amp probe to read. Since that
probably won’t do anything for you, what about dedicating a (something
like
pure sine) 300 watt 12v inverter from Morningstar to it. Regarding whose
problem it
is; over the years we’ve had little problems like this, groaning
ceiling
fans on a Trace DR led one customer to be totally confident his
batteries were
low, lines across TV’s, smoke alarms the smelled like THEY were on fire
and I’m
sure yourself and others have had many more. Unfortunately, there’s a
misconception that “solar power quality” is better then the grid in all
ways. We’ve overheard solar customers explaining to visiting friends
and
family that their appliances run more efficiently and last longer
because they
are off grid. I suppose there truth to that but certainly can’t make
such
a blank statement. Seeing and hearing this thing got my “uh-oh” alarm
to
go off. So for quite some
time, both
in the proposal and the contract spell out that we have no control thus
offer
no guarantee nor are liable for damages over what appliances or
electrical
devices will or won’t work on this system. Thankfully we’ve never had
to
pull this clause of the contract back out and of course would bend over
backwards as I’m sure you are to help the customer out. Travis Creswell,
Ozark Energy
Services, Hi, Allan~ I'm replying
off-list because
I think you might get more valuable answers from other participants,
but: This
sounds to me like an issue which could be addressed by adding a
capacitor to
the AC input on the heating system. You'd certainly want to try that
before taking
more drastic measures to help the client. I had something similar arise
with a
Trace inverter some years back. The Trace techie had only general
suggestions
but I took a stab in the dark and the system has now worked fine for
years. I can't recall if I
used a
start capacitor or a run capacitor, and I can't recall how I hooked it
up,
either. I'm heading out of town but wanted to at least give you this
suggestion. I think it was a start capacitor and those are available
now in a
variable setup where one unit can be jumpered to provide various
microfarad
capacities. Johnstone Supply has that part; other HVAC suppliers may
also...and
you might even get the hydronic heat guy to help acquire the part, etc.
The
little ones are about $100, IIRC. If you wire in one of the variable
units you
could start with a low capacitance then try higher values until things
smooth
out. Mick Abraham,
Abraham Solar, I wonder if a work
around
might be to run the igniter off a relay activated by the original board
and fed
by the inverter direct? I have seen things not start when the charger
was
drawing off the generator, not Magnums but old Hearts. Bob Ellison, RE
Ellison,
Theresa NY Have you tried a
different SW
inverter at the site? There is a difference between brands. Also, have
you
tried a "clean" waveform gennie like the Honda inverter series?
Finally,
I don't think that most manufacturers will guarantee that their
waveform will
power a specific load. Ezra Auerbach,
DragonSun
Consulting,
David Katz,
President, AEE
Solar, Try this: Add a
semi-large
load to that inverter and then see if the igniter works in addition to
that
load. A lot of times, a sine wave inverter
will clean up its waveform some when loaded due to inductances. Yes, even inverters designed by ex-Trace
Engineering and/or Xandroid engineers. BTW, I checked that company's
forum and
this same basic question showed up, except it was a generator that had
problems. They couldn't answer it
either, except to say that separating (or connecting together?) the
neutral and
ground wires might fix it for some reason. Must be something I'm
missing there,
but I've seen stranger things, I suppose. boB Gudgel, Midnite
Solar, We've had problems
with
running some Toyo and Monitor heaters on some inverters. A friend of
mine has
successfully used APC computer UPS units - the sine wave versions, to
solve the
problem. I haven't tried this myself yet
but this guy's a really sharp tech and I have no reason not to believe
he's
right again. I believe you can get one
for under $300 so if you have just one piece of equipment that's not
liking the
Magnum's waveform it would be a relatively inexpensive fix. Greg Egan, Remote
Power,
Inc., I
know John Raynes and I am kind of surprised at his comments. You would
see a
voltage drop on one leg when unbalanced just as you would with any
transformer
but I doubt the waveform is distorted just from unbalancing the
transformer.
The transformer inside the MS-AE is just an autoformer the same as
having like
a T-240 outside the inverter so if one leg is loaded the voltage will
drop and
the other leg will probably go higher. If you were running an inductive
load
you can distort the waveform and with long wire runs it might be worse.
As
for the idle current the MS4448AE is 25w “on, no load”. I verified this
with
our test sheets and talked to our test techs and verified they actually
adjust
a pot on the control board for the lowest idle current. We think 25w is
pretty
good but?? Gary
Baxter, Magnum Engineering 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
is what we would suspect here thus Tony’s suggestion for a 50mf run cap
across
the input to the boiler. The switching frequency on our MS inverter is
80 Khz. Gary
Baxter, Magnum Energy, This may
be true
about high frequency switching interfering with something, but I
believe the
problem with this igniter 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
Gudgel,
MidniteSolar, Some of
the hot surface igniters
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? The boiler
controls might not function due to low voltage or poor wave shape. Darryl
Thayer, Darryl
Thayer and Associates, Allan’s
posted
response: 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 Allan at Positive Energy I
installed an
off-grid system with identical symptoms: OB VFX 3648 dual stack,
Buderus
GB142-24 boiler, Kohler 12 kW propane genny. The boiler runs fine on
the
inverter power, but will occasionally error out (6A) and shut down
while the
generator is running (usually after it has been on for hours). The plumber installed an APC uninterruptible power
supply/surge suppressor (not sure of the model) before the boiler, but
when
running on the internal inverter, the symptoms seemed to get worse. When running on just the surge suppressor
portion, the symptoms were the same as if the APC wasn't in-line. We've checked the grounding at the genny,
made sure the neutral was isolated except for the main panel, still the
same
problem. Seems this is a Buderus issue
(or at least not an inverter one) - see: I haven't
been
able to make the boiler run reliably when the genny is on, which is a
problem
in our climate, when the client goes away in the winter... Howie
Michaelson, Sun
Catcher, LLC, I don’t
know if
you can power only the part that is giving problems and not the big
pumping load? I had a similar problem
with an SW Trace. I installed a Exeltech inverter to power that load
specifically and ever since has worked fine. The guys at Exeltech make
a
waveform that everything likes. Just a thought. Jay Peltz,
Peltz Power,
A few
years back,
we had a customer who was having similar problems. I don't
recall if it was a Buderus boiler, but the
generator was a Generac. This was a simple generator backup system. We
were
able to get the boiler to work reliably after adjusting the governor on
the
generator so that it ran at 60Hz under load. As I recall, it would then
drift
above 60Hz when unloaded. If you
were to try
a UPS, it would need to be a dual-conversion type to make a difference,
otherwise it would just pass the generator power straight through. True
dual-conversion UPS units are very expensive... Probably costing more
than the
cheap generator in many cases. Hans
Frederickson,
Frederickson Electric, Port Buderus' response: Howie Michaelson wrote: Hey Dan, I have had a persistent issue with a Boderus low mass boiler at one of my off-grid clients (dual stack VFX3648's, FM80, FNDC, etc. It goes into error sporadically, perhaps after a longer generator (Kohler 12 kW propane) charge run, maybe as it (the generator) shuts off. We tried to isolate the boiler's power supply with a small UPS with now luck. Outback couldn't help. Seems Boderus may know something about this issue in regards to generator/inverter setups, but the install base is so small they choose to ignore it. Don't know if this is related, and I have no solutions after many attempts at fixing it. Sorry...Howie |
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