Is a Cold Start Oil Burner Appropriate in a Cold Climate?

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Old 03-04-14, 03:37 PM
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Is a Cold Start Oil Burner Appropriate in a Cold Climate?

I have a "Superior Boiler" SO-130 Oil Fired Boiler.

We have a 1200 sqr. ft. ranch and an old Burnham Indirect Hot water tank (Amtrol makes it now).

I am using a 7224U Honey Well Aqua Stat and a Taco 502-4 Switching Relay for Zone 1 (the baseboard in the house) and Zone 2 Priority for the Indirect Hot Water.

Needless to say, the oil burner was seriously jerry rigged with an old 8124A Control (Triple Aquastat) that eventually failed (and quite epic).

I replaced it with a 7224U and had previously installed the 502-4 to correct many defects in the system wiring for the indirect hot water and the zone 1 baseboard.

I have been reading on this forum (after having determined I had a bad aquastat...) may instances of "cold start" applications.

Is Cold start appropriate in my circumstances? (I live on a mountain in CT) Or will it defeat the indirect hot water tank on zone 2?

I really don't understand the concept behind it, I know I can set cold start very easily on the aquastat, however, is it appropriate here given that it's so damn cold in the winter?? Is this actually efficient or should I just let the burner run a cycle of like 130-180 as the LL/HL with a 10/10 HLD/LLD ???

I have the 502-4 wired to operate as house thermo to TT for Zone 1, indirect HW thermo to Zone 2, TT to TT on Aquastat. ZR/ZC jumped in the 502.

The other connections are proper for the circulator for Zone 1 and the relay controller for Zone 2 and the power to the taco box.

Really, what I'm getting at is: Is cold start beneficial to me? And if so, is my stuff set up correctly for it?

Thanks,

Don
 
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  #2  
Old 03-04-14, 03:43 PM
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Hi Don, welcome!

the oil burner was seriously jerry rigged with an old 8124A Control (Triple Aquastat) that eventually failed (and quite epic).
I'd actually like to hear the epic tale if you would be so kind!

Since the 7224 is easily configured for cold or warm start, I would recommend that you run cold start and see how it goes.

With an indirect there should be no need to stay with the warm start.

I'm sure you will realize some fuel savings.
 
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Old 03-04-14, 04:01 PM
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The "Epic"

The epic was the 8124A just decided about 2 weeks ago to ignore it's high limit function and was basically running the boiler to about 230-240F, I was getting some strange noises from the baseboard and man, the heat was great! (Er steam)

I actually changed the temp/pressure gauge thinking it was broken... (must be right?? lol)

It wasn't broken. It was something to do with the temperature sending unit or the actual white limit block being outta whack. So needless, I replaced it and now I have more normalized temps. I adjusted the HL and it disregarded it each time, so I decided it must be the box.

Now the boiler appears to be correctly operating within normal ranges/parameters.

I will try cold start, I just did not want to waste oil, a friend of mine was telling me he thought that would be a tremendous waste of oil to heat up all that water from cold. Which prompted the question.

As to the jerry rigged issue, the indirect had been wired into the 8124A about a year ago... (and was not even functioning). The "hot water" in the tank was actually coming from the tankless coil on the boiler. They connected the blue relay wires to I think the L1 hot in the old box and the tt wires to tt (both thermos) and I think they also did the circ to c1/2 and the power for the relay in the brain of the indirect to c1/2 as well.

Thanks,

Don

PS Just set LL to OFF.
 

Last edited by donbrownzd1; 03-04-14 at 04:12 PM. Reason: Set Cold Start
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Old 03-04-14, 04:47 PM
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Your tale begs prologue!

This is the reason that many jurisdictions require a 'redundant auxiliary high limit' control. This control is wired in 'series' with the 'primary operating' high limit and will shut down with a 'hard reset' (button needs to be pushed and alerts homeowner to fault) in the event of overtemp. It's usually set about 25F HIGHER than the operating limit.

I will try cold start, I just did not want to waste oil, a friend of mine was telling me he thought that would be a tremendous waste of oil to heat up all that water from cold. Which prompted the question.
A lot of this depends on the volume of water in your system, which is a question that should be answered. You've got FIN-TUBE baseboards? or CAST IRON? If fin-tube, very little water in them. I'm not sure the water volume in your boiler, would have to look up specs... would you happen to have manual for boiler? It should say in there someplace. Unless it's quite old, chances are that there isn't more than say 10 gallons in the boiler itself. So, let's say there's ohhhh... maybe 15 gallons in the whole system. That's not really "... all that water ...".

During the winter, the boiler for the most part is not going to 'go cold' between firings anyway. ESPECIALLY THIS WINTER! So that point is moot for the most part in the winter.

In the summer, it's not going to take a lot to heat up the water in the boiler and the coil inside the indirect.

Yes, the boiler MAY burn a little more fuel during a cold start, BUT the fact that the boiler isn't burning fuel keeping itself warm 24/7 will more than offset that little extra needed for a cold start.

The "hot water" in the tank was actually coming from the tankless coil on the boiler.
Presume it's still piped that way? Probably should not have been but really, there's no harm in 'pre-heating' the water into the tank, with the exception that it could get TOO HOT. If this is being done, there should really be a 'tempering valve' to limit the water into the indirect to about the same temperature that the indirect is set to deliver. You should also have a tempering valve at the hot outlet of the indirect. This tempering valve should be set to 120-125 which is a 'safe' non-scald temperature. This also allows running the indirect a bit higher, say 140, which kills many waterborne pathogens, such as Legionella, Giardia, and others that THRIVE in 115F water. Google those terms for more info.

more...
 
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Old 03-04-14, 04:50 PM
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Need a little more info on the indirect install...

Is there a separate pump for the indirect?

You said this earlier which confused me a bit:

The other connections are proper for the circulator for Zone 1 and the relay controller for Zone 2 and the power to the taco box.
What exactly do you mean by " ... relay controller for Zone 2 ... "

If you have two pumps, one for the central heating, and one for the indirect, there shouldn't need to be any 'extra' relay controller, just the SR502 should be enough...
 
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Old 03-04-14, 05:29 PM
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I live in Central to Northern NY and it is pretty darn cold here. I have mine for cold start and only issue I have is not even directly related to the cold weather. Sometimes in the shower if the Indirect is near the lower end of the differential and the boiler is at room temp I will have 2 or 3 minutes of warm , but not hot water. It quickly heats up though. I also run a wood stove pretty much 24/7 in the basement so there are some instances when the boiler cools in the winter too, but again it only takes a few minutes to bring the temp up and get the heat going.
 
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Old 03-05-14, 05:47 AM
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I've seen too many boilers that were set for cold start ending up with "cement" accumulations in the flue passages, especially pin types. It gets so hard you can't brush it all out and as it builds up the heat transfer goes down. In concept cold start sounds good but for the little amount of fuel used to keep the boiler at around 100-110 I think it pays off.

As far as the indirect, some boilers are so slow to recover that you will end up with a tank full of cool water before it starts to get hot thus requiring a longer run cycle to bring it up to temp.

Just my observations over the years.
 
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Old 03-05-14, 10:42 AM
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In response to the above posts:

#1: I agree that NJTrooper's idea of a secondary high limit is a good one, certainly can't hurt.

#2: I have a 1200 sqr foot ranch with approximately 52' linear feet worth of base board-- standard Slant Fin style-- (fin over copper pipe).

#3: The indirect is a Burnham PAL-41. It has a temp control on it's base and a electro mechanical brain comprised of several relays (according to the schematic near the switch on the base)

#4: The indirect has a Taco 007 3/4" circ. plumbed into the return side of my boiler (off the return line).

#5: The indirect has control over the circulator pump by way of it's relay brains, and said pump is wired into the brain.

#6: The wires to the indirect are as follows: TT, H/N, and 2 violet wires. The violet wires seem to allow the relay to close? Or energize the relay so it can decide to allow the circulator to run.

#7: Connection is as follows: Taco SR 502-4 is powered by line from aquastat, Z1 = TT from house thermo, C1/C2 to Zone 1 Circulator. Z2 is TT from indirect thermo wire, C1/C2 to VIOLET wires. (Like I said, the circ pump on Zone 2 for the indirect is wired into the brains of the PAL and is controlled by it's circuit).

#8: I have a trade account with FW Webb. One of the sales reps recomended a zone switching relay controller as an easy way to solve the issues.

#9: In response to "If you have two pumps, one for the central heating, and one for the indirect, there shouldn't need to be any 'extra' relay controller, just the SR502 should be enough..." -- There is only 1 SR 502-4 2 Zone Switching Relay. I think the confusion was, the Burnham PAL-41 has it's own set of relay's forming a brain in the base of the unit. (The violet wires from the PAL-41 go to C1/C2 for the Zone 2 in the SR 502) The thermostat control is also tied into the "brains" of the PAL 41.

Hopefully, this is wired correctly, as everything appears to be working correctly.
I would love a manual on my boiler -- a Superior Boiler Company SO-130 and/or one for the PAL-41. (Not the amtrol model, but the original PAL-41)

I think that answers all the questions you all posed to me. Sorry for the delay.

Thanks,

Don
 
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