Peerless Pinnacle blown fuse

Anferny

Hey guys, I'm new to the site but have heard about it many times during the last few years of reading Plumbing and Mechanical. And of course now I enjoy reading Dan's articles too!

Anyway, I went on a call this morning for a 400K BTU Peerless Pinnical boiler which was inop. I found the 6.3 amp slow blow fuse on the board was blown. I looked everything over real well to see if anything looked bad, damaged or out of place before replacing the fuse. Everything was visually OK so I replaced the fuse and switched the power back on. The boiler kicked off and ran just as it should. As it ran I poked and tugged at the wiring and tapped on the controls and what not with my screwdriver handle to see if there may have been an intermittent short somewhere which I could make occur. No deal, it just kept running as it should. I know that failure or malfunction of most of the sensors and controls will throw a fault code, but I'm not too sure just what has to happen to pop the fuse. Any insite would be apperciated, as I'm honestly pretty green in the service and repair market. I wouldn't consider myself helpless, but I haven't had my face into much more than a hand full of Lochinvar Knights, and and a few NTIs. Thanks, in advance.

Anferny

????????

Nobody on this one? From what I understand this is a green Munchkin with Peerless stickers on it. By reading a couple other postings it sounds like Peerless tech support doesn't know much about em.

billtwocase

give it time

someone will take a stab at it. I do strictly oil, and have not had the pleasure to work on either of those beauties, but have seen many a thread on here in regards to problems. I would also try to search the site for an older thread. It may have your answer. Good luck

furnacefigher15

I would

Imagine the fuse is on the low voltage side. If that's the case, I would be looking at the thermostat, or boiler demand input wires for shorts to ground.



If the fuse is on the high voltage side, I would be looking at the blower motor and the pump for worn bearings, or shorts.



In general fuses blow for one of two reasons. A short to ground, or a load that is too high ie a motor drawing excessive amps due to a bad bearing.

Anferny

good point

I didn't even consider the low voltage side as a possible cause. There are 5 heat zones running through a zone controller, with the XX running to the boiler as well as 3 120 gallon Peerles Partner DHW tanks each with an aquastat, running in parallel to the DHW contacts in the boiler. I haven't heard anything from the homeowner about the system being down again, so I'm not sure where I'm going with it yet. Thank you very much for the input though.

icesailor

Munchkin Fuses:

It's my experience that fuses sometimes blow. Sometimes, it seems like FM.

* Magic.

Sometimes, the Sun, Moon and a certain star must align along with a Neap Tide. Then, due to the special energy generated by this phenomenon, the fuse blows. It won.t happen again until this Perfect Storm occurs again.

Those of us who do a lot of troubleshooting, are aware of this odd occurrence. If you wonder why you didn't get any responses, its because we feel we might look foolish trying to explain the unexplainable.

I know I'm foolish but at my age, I really don't care anymore. So, in a few words, it's unexplainable. Especially with the information provided.

icesailor

Magical Occurences:

Which fits in perfectly with my point. With all those things able to align, it could be anything.

furnacefigher15

No problem

I unfortunately run into this type of problem a lot.



I usually remove the control wiring, and isolate each wire (on both sides). Then one at a time test each wire to ground, and also to the other wires. There should be OL (open loop) at all points. If anything reads ohms, that's the problem. A lot of control wires get stapled to floor joists, or wrapped around nails. I have also found the old 18 gauge paired wire that had its own metal casing to be troublesome. Also rodents cause a lot of trouble chewing on wires.



When in doubt I replace the wires

Anferny

intermittent

i replaced the blown fuse on Monday, watched the system run to see if it would fault out, or blow the fuse again, but it didn't. So as of today i still have not heard anything from the home owner. I have no problem running continuity tests of the circuits to ground or to power, but if I'm dealing with an intermittent problem, I'll just be peeing into the wind until the fault occurs again, no? Could the wiring from the stats to the zone controller cause the fuse to blow even though they are wired into the zone controller? And then from the zone controller's XX terminals is where they (indirectly) tie to the boiler controls. I wouldn't think so, but...? The zone controller, boiler, DHW tanks and all of their related wiring are in the same room and accessible, so I can check them out and/or replace as is necessary. The stat wiring is way buried in the walls and ceiling. Inaccessible.

One thing I did notice was a mouse trap on the mechanical room floor which had seen some activity. I have done other miscellaneous work in this house before and I know that trap wasn't there before. When I say "before" I mean 2 months ago. So I can't rule out the rodent destruction idea either.

Alan_13

circ

on munchkin 80 had a fuse blow a while back, traced and replaced a circ being powered thru the board. all ok now

furnacefigher15

Rodent in room?

That is the likely culprit.



The other possibility is the xx terminal not closing completely due to trouble on one of the zone inputs.



For example: your fury foe chewed some wiring to the zone three t stat, causing more impedance then needed, and therefore voltage drop/loss. Well instead of the zone control seeing 24 volts from the W input for that zone, maybe it only got say 18 volts. So, instead of causing the XX terminal to close fully, and make the boiler fire, it was chattering a little causing the boiler control circuit to have higher amp draw.



What I'm really getting at is that even though the circuits are isolated, they do interact with one another.



Usually the problem gets worse, and more frequent. And, when it does, that's when you will find it easiest to get to the bottom of.

Anferny

RE: circ

Alan, do you recall if there was more than one fuse located on that board? The fuse I replaced is the only one there is. I still haven't a clue if it is line voltage or low voltage since I have not yet been back to the house to do any testing/probing.

Anferny

Re: rodent in room?

That seems to make sense. I didn't know if the stat wiring could cause issues like that but the scenario you put out there sounds possible. And, yes. Once it becomes more of a "hard fault" I should be able to locate it. Unless, of course, this was just a fluke as icesailor suggested. Time will certainly tell.

Alan_13

fuse

1 fuse on board, pita to get at.  Radio shack carries them

Anferny

one fuse

My reason for asking how many fuses were on that Munchkin board was because there is only one fuse on this Pinnical board. I don't want to assume that these have the same controls and boards, cause I just don't know if they do. I will assume (bad idea, I know) that the single fuse on this Pinnacal board could be a line voltage fuse which is like the Munchkin that you had the pleasure of servicing. Does anybody have a link to a good schematic for the Munchkin/Pinnical?? Maybe I can learn something from it before I get another no heat call on this piece.



I did pick up some fuses from Radio Shack after leaving that call :-)