need electrical help

jimmyc

Please ask questions if i dont explian enough. Im installing two boilers know the piping but am stuck on the wiring. Ha e piped many before will be the first I wire

Jamie Hall

Um... err... starting where?

And what kind of boilers?  Steam?  Hot water?  What controls?



Honestly, if you are not reasonably current (sorry) on electrical work, it might be better to get a licensed electrician in to do the wiring, at least to the point of getting power, properly wired, switched and with proper circuit protection (and, if code requires, or you are so inclined, fire protection), to the boilers.



With two boilers the controls can get a little complicated, depending on exactly what you want them to do when.  Nothing impossible, but it isn't always obvious how to wire them.

jimmyc

thanks for the comment

Two crown gas hot water boilers running individually. The model is bali. The electrician will get 120 to the boiler but i dont know how to go about wiring the controls.

Zman

System

Zone valves? Single circ?

I think the taco control relays really clean up and simplify the low voltage side.

jimmyc

thanks for the help

Yes one will have two zones . Honeywell and the other is just providing one floor no zone valve. I need help putting all the wiring together from the zone valve and aquastat high limi. Together ..

jimmyc

thanks for the help

Yes one will have two zones . Honeywell and the other is just providing one floor no zone valve. I need help putting all the wiring together from the zone valve and aquastat high limi. Together ..

Zman

Wiring.

Unless you are installing external safety devices, the boiler is pre wired to handle all that.

Anytime the connection from R to G is made, the boiler will fire.

For the one zone system the t-stat can be wired to R and G.

For 2 zones, I would use a taco zvc403-4

SWEI

Floor zone

is this by any chance a radiant floor?  Why did you select the BWF?



Did anyone do a heat loss calc for this job?

jimmyc

will need external safety

Thanks z man .... yes i will be putting a guard dog lwco and a highlimit aquastat for safety thats the problem i have im stuck and confused with how to wire it all together

Jamie Hall

In most cases

(check the ratrings!) the best way to wire safeties is in series with the 120 volt feed to the boiler controls.  On the hot side of the 120 volt (never, ever, put a switch of any kind in either the ground or the neutral!).

Jamie Hall

I'm paranoid

and I don't want any chance of something turning a system on which a safety has turned off.  I want power removed from that puppy until I find out what's wrong.

BobC

120 vs 24v

Another good reason to interrupt 120vlines instead of the 24v ones is it should reduce nuisance trouble calls. A switch handling 120v is much less likely to not make contact especially when you know they will use the cheapest POS switch if the bean counters have anything to do with it. It costs money to make a good reliable dry contact switch for low voltage and low current environments.



Reduced trouble calls and a safer environment for those working on the equipment is a win win all around. In some cases you might not have the choice but if you do, choose the higher voltage loop to put the safety in.



Bob

Zman

120

A agree that in most cases 120 volt is the best choice.

Unless the boiler manufacture provides terminals for external safeties, you are rewireing the boiler. The potential to make a mistake that either voids the warrantee or creates an unsafe operating condition is high.

icesailor

Electrical Questions:

In my worthless and unasked for opinion, if you must ask the type of questions you are asking, you are in no way qualified to wire your boilers. You need to have a licensed electrician wire your boilers.

 In Massachusetts, a licensed Oil Burner Technician is allowed to wire a replacement boiler from the safety switch. But not a new installation from the panel. You have two boilers? In a multi-family or commercial application? That doesn't qualify a homeowner/DIY and handymen "electricians".

Does the installation of these boilers have to be permitted and inspected in your jurisdiction? If so, will it pass inspection if you do it? Or will you just not have it inspected.

Not to be a click, but from your questions, I KNOW that I am far more qualified to wire boilers from scratch and I am licensed to do so. But licensed electricians (the good ones) are far more qualified than I to wire boilers. That's why I always had qualified licensed electricians wire my boilers.

Then, the paranoia in me takes over and I worry about implied liability from good intentioned advice done wrong and the giver of the free advice has a problem when something goes wrong.

BobC

I agree

if a boiler comes prewired with safeties in the 24v line it's best to leave it like that in case any question ever comes up that you don't want to be soley responsible for. It's not that you wouldn't do it right but you don't want to get in the cross hairs of some officious insurance inspector.



Bob

Zman

Wiring

Some boilers provide a 24v terminal for external safeties, which is normally jumpered.. In that case 24 volt external safeties make a lot of sense.

Wiring them in series with the t-stats will "work", I think it makes for difficult troubleshooting down the road,

I have seen too may jobs where someone has accidentally bipassed the boilers onboard safeties while trying to add externals. Even if the original installer gets it right, you don't want to encourage the next guy troubleshooting the system to mess with it.



Unless the manufacture gives you a clean way to install 24volt, I would go with 120 volt.

Jamie Hall

Leave all the factory wired

24 volt stuff alone.  As has been noted, warranty issues.  However, that doesn't prevent you from putting anything you want into the 120 volt feed to the unit from the switch box!  So... you have your regular cutoff switch somewhere, then in series to your new second LWCO, then in series to the second pressuretrol, power the automatic water feeder off all that if you like, then -- finally! -- to the power input to the boiler.

ChrisJ

Voltages

Wow, this thread has gone way off track eh?

Some feel 120V rated controls are better than 24V ones?.  This is a very bad assumption to make in my opinion.

I don't see why this would be the case and am curious to see some statistics on 24V controls working @ their rated voltage vs 120V ones also  working @ their rated voltage under the same conditions.

I see no reason the 120V ones would be better when working under their intended conditions.  If anything I would expect heavier contacts on the 24V switches / relays rather than "cheaper". 



Does anyone publish MTBF on safety controls for boilers?

Zman

jimmyc

My posts where directed to the OP "jimmyc"

The confusion has come from someone introducing a new system.

The Wall works much better when people don't do that.

Jamie Hall

MTBF figures

would be interesting.  I've never seen any...



My preference for 120 volt safeties isn't based on that, though, but on a desire to kill the mains power feed to the unit if a safety trips -- as distinguished from a true control, such as a thermostat.



As to the durability of the switches.  As someone further up the thread noted, it is more difficult to make a reliable low voltage dry contact than it is to make a high voltage one, simply because for a given contact resistance the low voltage circuit if more affected.  Which is not to say it can't be done -- there are millivolt switches which can withstand a million cycles.  They will cost a little more, however (until you get up to even higher voltages -- 660 and up -- where you need auxiliary contacts and arc suppressors and things begin to get actually interesting).



Bottom line on that -- if you can't find a mercury switched thermostat, vapourstat or whatever, you're stuck with the dry contacts and you're pretty much at the mercy of the bean counters at the manufacturers!