Plug my boiler in? Generator question

wildrage

I have a commercial grade 250,000 btu Wells boiler. No pumps. Only thing that's on electric is the gas valve and safety switch...so i'm assuming it takes very little electricity to run.

I experienced a 18 hour power outtage during a windstorm this week. 15 degrees outside with 50mph wind gusts. Thankfully the temperature didn't drop to far in my house, but I told myself 'never again.'

I eventually want to get a whole house generator, however, I want to take time to price it accordingly, size it accordingly, and get it installed with all of the proper transfer switches, etc.

That being said, I picked up a high-end 2400 watt portable generator. I figured I could use it in the future for camping, etc.

I want to do this safely. No backfeeding into the house, but I also don't want to do the whole home system until i'm ready, priced it right, and have it sized right.

Question is - Right now boiler has it's own sub panel, wired right into the breaker. I read on another forum that you could 'plug' your boiler in. In that I just cut the wire, wire the subpanel to an outlet, and wire a 3-prong plug to the boiler - and just plug it into the outlet. My reasoning is if the power goes out again, I just unplug the boiler from the outlet, and into the generator. Article I read also aledges that this is totally safe and meets code.

Any thoughts? I'm fairly good at electric, and surmise this would be a 15 minute project.

Ironman

As long as you arrange it so that nothing else is back fed from the generator, you should be fine.

Campyman

Odd are high it'll work just fine. If you tried to run your whole house on the generator this becomes a lot more complicated to do safely. But if you're just using a cord than go a head.

Zman

You might also consider using a computer ups in the mix. It would run your boiler for short periods without having to fire the generator. It will also help clean up the potentially "dirty power" generators often put out.

ethicalpaul

I like @Zman 's thinking. That's way more generator than you need for a gas valve.

MaxMercy

wildrage said:

I read on another forum that you could 'plug' your boiler in. In that I just cut the wire, wire the subpanel to an outlet, and wire a 3-prong plug to the boiler - and just plug it into the outlet. My reasoning is if the power goes out again, I just unplug the boiler from the outlet, and into the generator. Article I read also aledges that this is totally safe and meets code.

Code would depend on the jurisdiction I suppose, but if you replace the boiler's wiring with a three prong plug, then unplugging it from a wall outlet and plugging it in to a generator or extension cord to a generator is no different from and is as safe as plugging in any AC powered device.

wildrage

ethicalpaul said:

I like @Zman 's thinking. That's way more generator than you need for a gas valve.

Yea that's a good idea too. Was thinking i could use it for some other basic appliances too (since the power is out after all)...obviously nothing that produces heat or needs to run a compressor, but some basics.

bucksnort

Does your code allow for a connection for your furnace to be "temporary" or does it need to be permanently connected?

Zman

I don't think the solution is code compliant. It also is not dangerous. Mine is wired that way and if it ever becomes an issue I will just rewire it.

EdTheHeaterMan

You could plug in the heater, a radio, a few lamps, and even the more important Beer Refrigerator.

Lyle {pheloa} Carter

This summer my electrician will be installing a generator interlock, it allows the generator to feed the house without back feeding into the street. Obviously you cannot draw more power than the generator creates. So nobody can turn on any high draw appliances. Much more competitive than a transfer switch, good for long term use or temporary use until a permanent generator is installed. Website states it's legal in all 50 states. This way you can run the radio, a few lights, and the all important beer fridge without all the extension cords.

ttekushan_3

I set up my little boiler just that way when I finally installed steam heat in the house. 

I had considered going completely power pile operation but I didn’t really want to lose the flue damper, probe type lwco, and electronic ignition. I knocked like 45% off my monthly wintertime electric consumption in the conversion from FA, so yeah you could probably plug it in the other end of your Christmas tree lights without issue either. Well, except that the Christmas tree interface is frowned upon these days. I’ve heard. 

mattmia2

the listing of the boiler probably says it is to be connected to permanently installed wiring methods only so technically it is a violation of the electrical code because of that. that being said, as long as you connect it so it is permanently connected to the buildings equipment grounding system even if the plug is unplugged(for example put a junction box on the equipment, run power to that, connect the cord out a gland in the side of that box, put the receptacle in that box and bond all the grounds together and to the box), it should be fine. current code will probably require that receptacle to be gfci protected. i would use a twist lock so that nothing else can get plugged in there. ultimately it would be up to the ahj.

Tim Potter

You could use something like these to be code compliant.

https://www.homedepot.com/p/Reliance-Controls-Furnace-Transfer-Switch-TF151/202216476

or

https://www.amazon.com/EZ-GENERATOR-SWITCH

veteransteamhvac

A good sized, quality computer UPS is my go-to for my steam boiler backup power supply. And, yes, it's as simple as cutting a 3 prong plug and wiring it to plug into the UPS. I keep the UPS plugged in all the time to keep it charged. The longest I've gone with the power off is 3 days, no issues whatsoever with the gas valve or transformer. It's something really nice to have your boiler operating perfectly while the snow is falling and the power is off.

My neighbors with hot water systems aren't so lucky but I suspect that some of the affordable small generators could handle the demands of the circulator with no issues.

HomerJSmith

I might add, when buying a generator, always buy one that has a low THD (Total Harmonic Distortion) especially if using it for a computer or any device with sensitive circuitry.

My stand alone generator has less than 5% THD. Many are rated at 12%, so they don't advertise the THD.

OK, Homer, what is THD? It is the distortion in the AC sine wave. When using a generator you might need a line conditioner for sensitive circuits to function properly.

pecmsg

HomerJSmith said:

I might add, when buying a generator, always buy one that has a low THD (Total Harmonic Distortion) especially if using it for a computer or any device with sensitive circuitry. My stand alone generator has less than 5% THD. Many are rated at 12%, so they don't advertise the THD. OK, Homer, what is THD? It is the distortion in the AC sine wave. When using a generator you might need a line conditioner for sensitive circuits to function properly.

Seeing how almost everything has some type of computer sound advise. 

mattmia2

My guess would be that the noise comes mostly from the brushes for the field coil and could be filtered out. The UPS or the inverter solution is kind of like suggesting RO for every water quality problem.

Zman

mattmia2 said:

My guess would be that the noise comes mostly from the brushes for the field coil and could be filtered out. The UPS or the inverter solution is kind of like suggesting RO for every water quality problem.

The UPS was suggested mainly because there is very little electrical load on the system. It would run just off the UPS for the better part of the day. The fact that it will clean up the power is icing on the cake. Generators can put out some ugly power, especially when there is not much resistive load.

Jamie Hall

mattmia2 said:

My guess would be that the noise comes mostly from the brushes for the field coil and could be filtered out. The UPS or the inverter solution is kind of like suggesting RO for every water quality problem.

That would be the source of high frequency noise, yes. However, much of that will be filtered out by the inductance of the armature coils.

That said... there are some really fascinating tradeoffs which can be seen in the various ways generators were -- and are -- built. Back in the day (I have one) the actual alternator head -- armature with its windings, sliprings, and field coils -- was astonishingly heavy. There was a lot of iron in there, and a lot of copper. The things had to run at a constant 3600 rpm, as they were two pole machines. Noisy. Gas guzzlers. But -- the better quality ones gave power which was remarkably free of harmonic distortion (governed almost entirely by the geometry of the field iron and coils), with very little noise and, because of the sheer weight of the armature, excellent frequency stability (not that you'd want to run an electric clock off one, or a synchronous motor drive high fidelity turntable!). They also weren't cheap... As the drive for lighter weight, better fuel economy, and lower noise -- not to mention less expense -- things changed, and now some of the most popular small generators (for, I will admit, good reason!) are much lighter, much quieter, and have much better fuel economy (particularly on part load). But... whether they are constant speed or particularly if they are variable speed, the the loss of the massive iron pole pieces and the copper windings has given rise to having to keep the THD, voltage, and frequency stability in line by electronic means instead. And some do a lot better job at this than others, as the electronic gadgetry (particularly in higher power units) is not inexpensive...

SuperTech

I was pleasantly surprised when I lost power for 4 days I was able to run my boiler with my cheap harbor freight generator.  Lots of electronics on my boiler. L7224U aquastat with outdoor reset module, R7284U primary control,  Tekmar zone control board,  three ECM circulators, two VT2218s and a Alpha 2. I honestly thought I would need a line conditioner. Still might get one just in case.

MaxMercy

I've been looking for a portable generator with two things: low harmonic distortion and propane power and about 8KW or so. Plenty of choices but I haven't been able to find a combination of all three.

sunlight33

MaxMercy said:

I've been looking for a portable generator with two things: low harmonic distortion and propane power and about 8KW or so. Plenty of choices but I haven't been able to find a combination of all three.

Here: https://westinghouseoutdoorpower.com/collections/generators/products/wgen12000df-generator-dual-fuel

ethicalpaul

These look pretty good and are great for camping etc: https://www.amazon.com/dp/B07D29QNMJ

Sal Santamaura

Jamie Hall said:

...excellent frequency stability (not that you'd want to run an electric clock off one, or a synchronous motor drive high fidelity turntable!)...

Since 2016, when the Federal Energy Regulatory Commission eliminated the requirement for grid frequency stability, running those things off utility power is not a great idea either. I regularly need to reset the time on those few clocks still in our home that rely on 60 Hz as their reference. Around here, drift has been in the range of one to two minutes per month.

MaxMercy

sunlight33 said:

MaxMercy said:

I've been looking for a portable generator with two things: low harmonic distortion and propane power and about 8KW or so. Plenty of choices but I haven't been able to find a combination of all three.

Here: https://westinghouseoutdoorpower.com/collections/generators/products/wgen12000df-generator-dual-fuel

I wonder if that's new. I looked at Westinghouse last year but the ones that were low THD were not propane and vice versa, although I might not have looked at it as it's bigger than I really need. Thanks for the link.

HomerJSmith

Costco has tri fuel generators that run on gas, nat gas, propane in the 7-8 KW range (Firman and Champion).

Champion makes a propane-gas generator with a low THD in that range. Gasoline has the most kick in getting the most current from your generator.

ChrisJ

I wanted a portable generator around that size and the only way I could get it was to build my own from an older whole house generator.

In my case mine is good for 10kw on lpg but I run it on natural gas so I get less.  Not sure how much less but it did 8kw easily.  I suspect it'll do about 9kw before my voltage and frequency drops too much.  The alternator it self is good for 50A per side x2.

Its rated less than 5%thd but in reality who knows.  

I can say stability wise it behaves much different than any portable generator I've used.  It seems to handle load changes easier etc and just acts like it has more authority.

See what you can find floating around used.  Most can be made to run on LPg fairly easily.  You might be able to make out real good for not too much money.

weil_fail

that configuration should function just fine. I'm not sure about the electrical code, but the gas furnace at my old place was plugged into a wall outlet to run the blower, ignition, etc..

if I were you, I'd just have an electrician come put in a box and a plug. if they say "you can't do that" then you'll have your answer. if they do it, then you're good and it won't cost too much.

if they say "no", you can take the risk on yourself and either wire up a plug or replace the wire nuts inside the nearby box with some Wago connectors and when the power goes out, flip the breaker off, open the Wago tabs, and connect it to a plug that can go into your generator.

Ahead

Interlock kit and you've got anything you need powered. Wire up to panel, making sure that on the generator side the neutral isn't bonded (split any such bonding -neutral and ground, feed them separately and connect to the panel through the appropriately sized breaker). Make sure to note that the generator ought NOT be used as a portable generator/standalone power supply (unless you re-make the bonding).

I've been running an old 7.5kw diesel generator for years w/o any issues: 1800 rpm all day long; power output is dead steady; Onan/Cummins [Kubota diesel] with a modern voltage regulator board installed; won't trade this for anything! Most modern electronics have the necessary bits to handle imperfect power sources. I do, however, have my computers on UPSes to ensure that when I do a manual switch-over that they stay up (and this is likely the more important thing- minimize power-cycling, which is the hardest on electrical devices).