Cold start oil boiler for backup/mostly idle application

Ogramorr · January 5

Hello all

Appreciate the time and effort everyone invests here...

Context:
Have oil currently, switching (mostly) to heat pumps, but want to retain boiler for power outages and cold snaps.

Current boiler still works but is old.

Objective:
Would like to identify what's next before it’s actually needed.

Needs to be cold start (Planning to keep the current warm for now to keep it stable, but not an acceptable long term strategy)

Don’t need high efficiency.

Just needs to function reliably when called into service and not respond badly when that only happens infrequently.

Aware of at least one option but it feels a bit extravagant given the application, looking for recommendations for simple, easily serviced, ‘no frills’ solution.

Thoughts on options?

Thanks in advance

Ogramorr · January 5

Had this then restarted and lost - Zone 6a, 2400 Sq ft of average-ish construction, 30 something/40k btu, pretty standard fare…

EBEBRATT-Ed · January 5

What are you trying to do eliminate keeping the boiler warm? Do you have access to the wiring diagram and some pictures?

What ever you do it won't be reliable unless you run it occasionally

hot_rod · January 5

Is the boiler currently connected to radiators or fin tube baseboard? Or just a boiler sitting by itself?

Ogramorr · January 6

Appreciate the replies.

Currently connected and in use, turned the thermostat back up a few weeks ago when it got down into the teens and single digits. 108 feet of fin tube on two floors/zones. Honewell aquastat, 160/10, 180 for tankless coil, to be decommissioned (but left in place) when the HPWH setup is finished.

Looks pretty good overall but has some cancer that's not particularly reassuring

I know it can at least set it lower once the coil has been relieved of duty, and can roll the dice on taking it further when I have a plan in place for replacement if it goes poorly.

"What ever you do it won't be reliable unless you run it occasionally"

Not conceptual level problem with that. Could you elaborate on what run occasionally would look like for you, and perhaps what you might choose for replacement equipment for intermittent use if/when it's needed?

EBEBRATT-Ed · January 6

I would start it monthly during the heating season and run it for 3 hours.

Keep your eye on it for potential leaks.

A boiler that is kept hot all the time may leak when it gets cold. The tankless heater gasket is a potential leak source. The gasket dries out and gets stiff after a while

SuperTech · January 6

I would just replace that tankless coil gasket and then once a year torque the nuts to prevent that from happening again. That Peerless WBV appears to be in great shape and should have a few more decades of life in it.

It's really a shame that so many boilers rot out because nobody knows to re-torque the fasteners for the tankless coil plate.

HVACNUT · January 6

Just turn the Low down all the way. It'll recover a few times a day. With the obsolete primary and shaded pole burner motor, I'd exercise them. The boiler will never go to the high setting unless there's a call for heat.

The coil has studs and nuts rather than easy snap bolts, so a new gasket and a blank coil plate shouldn't be a problem.

Jamie Hall · January 6

Run it once a month as suggested, just to see if anyone's home. Once the boiler is at room temperature — a matter of perhaps half a day at most — it really doesn't care how long it sits that way. The comment on checking gaskets for drying out on the tankless coil is a good one, though. They will — but only if the boiler is drained.

EBEBRATT-Ed · January 6

@HVACNUT

I don't see the need to turn down or disable the LL if its just a back up and will be shut down most of the time.

pecmsg · January 6

that gasket is already compromised.
eliminate the HW

Install a blank and retighten the bolts several times

Get a heat pump water heater

HVACNUT · January 6

https://forum.heatinghelp.com/discussion/comment/1881089#Comment_1881089

True. I missed the "shut down" part. The WBV is a decent boiler. It'll be happy to sit.

One thing bugging me. Maybe its the camera. That does not look like 6 inch flue pipe to me. It looks like 5 inch.

EBEBRATT-Ed · January 7

@HVACNUT It does look small.

Ogramorr · 1:04AM

https://forum.heatinghelp.com/discussion/comment/1881091#Comment_1881091

[Discovered I had a draft saved, looks like I composed a reply and never hit post… Oops]

Blank and gasket ordered. HP water heater is already set, working on hooking it up.

"One thing bugging me. Maybe its the camera. That does not look like 6 inch flue pipe to me. It looks like 5 inch."

I think it's skewed a bit from taking the picture standing right in front of it. Opening on the barometric measures 6" across and the pipe is 20" around… Appreciate the callout to check though.

Update: Pulled the tankless coil and nasty blank. Bought a carbide scraper that did a nice job of cleaning up the mess underneath. Thankfully the rot was pretty well contained to the cover blank and sheet metal and didn't really get into the mounting face.

Set the new blank and gasket and replaced the bolts with a bit of anti seize and tightened down progressively in a criss cross pattern until good and tight. Perfect seal.

Appreciate the feedback.

EdTheHeaterMan · 1:48AM

Did you order the blank plate with the 3/4" tapping in the center for the aquastat?

This is a way to rewire the existing control to be a cold start control. No new parts needed, just a wire nut.

More details can be found in this thread:

https://forum.heatinghelp.com/discussion/comment/1798670#Comment_1798670

Cold start oil boiler for backup/mostly idle application

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