oil backup on Classic Edge (newbie)

[Richard Cosmore]

We just started up our new Classic Edge 750 the other day. It is my first OWB and It is hooked directly into our existing oil boiler which had been heating the house prior to our purchase of the 750. It was installed and is set up so if the fire goes out or if we don't feed it, the oil boiler will kick on when the water temp. drops to 140 degrees. The oil boiler is suppose to shut off when the water hits 160 degrees and it will continue to do this until the OWB is up and running again.

I am just wondering what to expect when the oil boiler tries to heat 300+ gallons of water that the 750 holds from 140 to 160. Will it run constantly or will it not be so bad?

The name plate on the oil boiler reads the following BTU ratings. Not sure how to decifer it.

DOE 147,000/172,000 BTU
IBR 127,000/150,000 BTU

 

[hondaracer2oo4]

You'll want to have a flat plate heat exchanger keeping the two systems seperated. Is this the case or did you depressurize your indoor boiler?

 

[Richard Cosmore]

The indoor boiler is depressurized. The outside boiler pumps directly into and out of the inside boiler. Shut off valves allow us to re pressurize the inside system during the non-burning season. During the cold weather months the valves stay open even when the outside boiler is not in use. This way the water will not freeze and will need to be heated by the inside boiler.

This is the part I am curious about and how able the inside system will be to heat the outside boilers water supply for a few days while I am unable to tend to the boiler.

 

[mustash29]

I grew up between Hanover & York, so I know the weather down there.

Sorry to say, but I think your plumber screwed you.

Is the 750 just sitting on a concrete pad or is it inside an outbuilding? Insulated building? What are you using for underground piping? How well was the trench insulated and protected from groundwater intrusion? How long of a run of piping?

These things are all going to radiate heat and be losses to the environment. If burning cheap wood they might not cost much. If you have to heat them with oil the cost could become significant in a hurry.

How big is the house? What is the design heat load? If you have to "back feed" heat to the 750 (and the ambient losses) while still heating the house (and domestic hot water?) on a very cold day I could easily see your oil boiler running nonstop.

 

[Richard Cosmore]

Here is the set up:

750 is on a cement pad; The run is just short of 100 feet; I used thermopex for the undergound line. The house is 2400 sg/ft and is an old log home. The current heat design has three zones. One zone for the old part of the house, One zone for the new part of the house and one zone for the radiant floor heating in the sun room.

As many honest opinions as I can get.

 

[Richard Cosmore]

If the inside system does end up being unable to keep up, Is there another way to hook things up (heat exchanger ) that will allow it to work better?

 

[maple1]

This sounds like a bit of a questionable install to me. Wondering how much input you had into it? Some of the things done should only have been done after close consultation with and agreement of the owner.

We can't tell anything about controls from here, which is a big part of the equation. But you will burn a lot of oil, if you are away for any amounts of time and your OWB fire is out for long enough for it to cool off enough for the oil to be keeping it hot. It isn't just the keeping 300 gallons hot - it is the doing of it in a fairly large heat loss situation.

Then there is the situation of having all your indoor system being an open system - and the increased corrosion implications of that. And possible functioning/circulating issues in being unpressurized - but that would likely come down to elevation differences between everything, something else we don't know about.

 

[Richard Cosmore]

I was totally going off what the dealer was telling me. He said the only downside of depressurizing the indoor system would be the possibility of corrosion in the system but if I was to keep the proper amount of inhibitor in it I would be fine. He said I just needed to be diligent about testing it every year. As far as the oil backup, he made it sound like the oil burner would be able to keep up with it fine as the heat loss would be low.

I am getting slightly anxious now that I hear what you guys are saying. Are there more downsides to depressurizing the inside system than what he told me? Where do you think my largest heat loss is.....the exposed nature of the boiler? If so, would building a insulated structure around it make things a lot better or just slightly better?

At what outside temp. would you guys be worrying about damage from burst parts from freezing in my current set up? I know 32 degrees is freezing but I am assuming if daytime temps get above freezing that will help mediate some of the low temps at night.

Should have got on here sooner......I KNOW