Help with DHW coil in oil-fired boiler

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Old 12-18-07, 10:22 AM
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Question Help with DHW coil in oil-fired boiler

I have an old Smith boiler for a one-pipe steam system that heats DHW with a coil. Recently, hot water pressure at all the faucets in the house has reduced to a trickle, making (hot) showers almost an impossibility. Cold water pressure is fine. Couple of questions:

(1) Since water pressure up to the coil seems to be fine, my guess is that the coil has mineral deposits blocking flow. I tried boiling the water in the coil by raising the Aquastat to 220 degrees and shutting off the cold feed to steam clean it, and the problem has not gotten any better. If replacement of the coil is necessary, is this a DIY job that someone without a lot of experience with boilers can do?

(2) The coil has never done a good job of providing hot water (until now particularly in the summer), so if I was to add an indirect tank, say a MegaStor model (also DIY?) will the clogged coil prevent the indirect from working properly?

Thanks in advance for any suggestions!:
 
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Old 12-18-07, 12:22 PM
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The coil would have the pipes removed abd left open. You wouldn't use the Mega-store with the domestic hot water coil. The coil would have the pipes removed and left open to avoid pressure build-up in a closed vessel. The boiler would than be wired for cold start. The existing aquastat may be able to be used for this. Use a properly sized three piece circulator. A call for heat or hot water will fire the boiler. In a call for domestic the aquastat will keep the boiler from making steam unless a call for heat is established before the call for heat ends. The key to making an indirect work off of a steam boiler is to have available tapings in the boiler at two different levels in the boiler. It does not work well supply and return both at the bottom of the boiler. What model Smith boiler do you have?
 
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Old 12-18-07, 04:07 PM
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The plate says it's a Smith No. 110L-1100L with a Carlin Model 100 CRD burner.

How do I know if I have the tapings to add the indirect? If they're indicated by knockouts on the boiler jacket (or whatever you call the steel case that surrounds the boiler) it looks like there are several of different sizes and at different levels.
 
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Old 12-18-07, 06:25 PM
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rbeck/circulator

Originally Posted by rbeck View Post
Use a properly sized three piece circulator.
Why a 3 piece circulator instead of a bronze or stainless wet rotor? You would need bronze or stainless in any case, would you not? I've read about doing this but never done it.
 
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Old 12-19-07, 06:24 AM
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Longevity my man! It moves more gallons as it is normally a short run. Just had a lot better luck with them. I have seen a lot of wet rotor circ's last about 5-8 years. The 3 piece I have seen last twice that.
 
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Old 12-19-07, 06:41 AM
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Unhappy Bypass the boiler and go electric?

Well from reading this forum, I know the pros seem to overwhelmingly favor the indirect setup, but I'm considering just going to HD and getting a decent electric and bypassing the coil. If I was having a whole new system put in, I would definitely go the indirect route, but with the age of my boiler, I'm not sure that the operating efficiency will be that much more with an indirect.

I guess this may be the quick and dirty route that many homeowners take when they want hot water fast for low up front costs. If you bypass the coil and put in a direct heater, then I take it you could still turn the Aquastat to the lowest setting or re-wire the boiler for cold-start?
 
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Old 12-19-07, 08:43 AM
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You can do what you stated but, an indirect can be connected to your next boiler so ity is not a waste. The stats state that an electric hot water heater for a family of 4 could be 30-50% of your electric bill. Are you ready for that with electric increasing over the next few years? Well water or city water? What is the hardness of your water?
 
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Old 12-19-07, 11:55 AM
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Catch-22

I don't know exactly what the efficiency rating of my Smith boiler is at this point, but given our extraordinarily high heating bills, I believe it's not very efficient.

On the one hand, I'd much prefer to put in a good quality indirect as you described, but while I'm handy, it seems the job is significantly more complicated than installing an electric.

To have a pro come out and clean the coil with acid will cost about $250 - which could instead go to the new heater or indirect.

The water is hard city water -- we have a water softener system installed (which also doesn't work right).
 
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Old 12-19-07, 12:06 PM
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If you presume very low efficiency, then I'd be very tempted to go with an electric WH. The pump alone for a steam system could be the same as the price of an electric tank. First though, you really should do an energy cost comparison.

Is the boiler gas or oil?
If oil, is natural gas available?
What's the price per kWh on electric, per gallon of oil etc?
 
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Old 12-19-07, 01:38 PM
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Who, you do realize electric rates are hovering near 20 cents per kWh here in the northeast, right?

Pete
 
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Old 12-19-07, 02:02 PM
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So the OP shouldn't do any energy calculations because you happen to pay that much in your area?
 
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Old 12-19-07, 02:26 PM
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I guess that means that I can't complain about paying a bit over 8 cents per kWH.
 
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Old 12-19-07, 02:36 PM
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furd, shhhhh... people will still freak out, because it's electricity and somehow a very expensive fuel. BTW, oil would have to 92% efficient to equal that at $3/gallon.

At 15 cents per kWh and 50% efficient on $3 oil you get parity and a greatly reduced initial cost. Best part is when you get the new boiler the tank can match so the system has more panache... hehe
 
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Old 12-19-07, 07:16 PM
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Bronze 3 Piece

Originally Posted by rbeck View Post
Longevity my man! It moves more gallons as it is normally a short run. Just had a lot better luck with them. I have seen a lot of wet rotor circ's last about 5-8 years. The 3 piece I have seen last twice that.
Rbeck: I understand the longevity but have you priced a bronze B&G 100 lately? Something else out there a good bit cheaper?
 
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Old 12-19-07, 08:29 PM
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Electricity vs. Oil

The figures mentioned by Furd are pretty much right on. In central Jersey we pay .15/kWH and around $3.20 for oil. Unfortunately, natural gas isn't available.

The low up front cost of the electric is nice (50 gal tank at HD is around $300). I'm not sure about it matching up with the new boiler (which is going to be needed soon), but I may paint some flames on the side of the new tank to signify all the cash my system is burning.
 
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Old 12-19-07, 09:52 PM
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Originally Posted by BringIt View Post
In central Jersey we pay .15/kWH and around $3.20 for oil. Unfortunately, natural gas isn't available.
Yeah, I know what you mean neighbor...

I run an electric WH ... cost me about $35 a month, two persons, and that's WITH a discount for timed water heat which I'm 'grandfathered' into. It's on it's last legs though and hopefully will soon be replaced with an indirect.

Sure wish I could plug a long extension cord into one of furds outlets ... furd, does the noise from the hydro plant you must live next to keep you awake at night ?
 
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Old 12-19-07, 10:11 PM
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I'd have to get my map out but I think the nearest hydroelectric plant to me is at least fifty miles away.

And that 8+ cent per kWH is the winter rate, summer rate is about a penny less. Nonetheless, SnoCoPUD has about the highest rate in Washington state thanks to Enron.
 
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Old 12-22-07, 04:51 PM
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Question Disconnect Aquastat?

Is there any downside to simply disconnecting the Aquastat after bypassing the coil?
 
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Old 12-22-07, 05:26 PM
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Aquastat

Before we could advise you on disconnecting the aquastat, we would have to know what controls you have & how they are wired.
 
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Old 12-22-07, 08:51 PM
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I'm loyal to oil but when you factor in the prospect of turning off an inefficient oil boiler all summer and running an electric water heater all year, you probably are better off with the electric. If you were planning on replacing the oil boiler in a year or two, I would suggest trying the indirect and then using a good efficient low mass, cold start oil boiler with the existing indirect.

Ken
 
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Old 12-23-07, 10:52 AM
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Question Aquastat Need to Rewire For Cold Start?

Thanks for all the responses, and Happy Holidays to everyone!

Grady: The boiler is an oil-fired Smith with Carlin burner. The feed and outlet pipes were disconnected at the DHW coil and left open. Wires to the aquastat (that was set at about 140 deg.) were simply disconnected. These wires going from the aquastat were going to a Honeywell controller by the burner which also handles calls for heat. So far the system is functioning fine but I've read a lot here that suggests rewiring for "cold-start."
 
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Old 12-23-07, 11:25 AM
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Aquastat

If you have removed the aquastat wires, it should now be cold start. Is the boiler maintaining temp?
 
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Old 12-23-07, 12:14 PM
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Thumbs up Aquastat

Originally Posted by Grady View Post
If you have removed the aquastat wires, it should now be cold start. Is the boiler maintaining temp?
The boiler is no longer running to maintain the temp setting on the Aquastat, if that's what you mean. I'm guessing I was just confused by the term "rewiring" for cold start, when clipping/disconnecting the wires is all that's involved.

It seems like everything is running fine (until the boiler starts to leak from the change in setup).
 
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Old 12-23-07, 02:26 PM
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Good Deal

The reason the "rewiring" question was asked is some boilers have a line voltage aquastat. Your's sounds like the more common low voltage variety. You may not get leaks. So do-some don't.
 
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