Gas gun versus new gas boiler

silow

We're converting from oil to gas as part of a renovation that added a room and expanded another room in the house. Our Peerless oil burner is only 5 years old. One option is to get a gas gun for the current oil burner, which our plumbing/heating contractor says should have enough capacity but 'it will be close.' The alternative is to replace the boiler with a slightly higher capacity gas furnace. Any suggestions?

KC_Jones

silow said:

We're converting from oil to gas as part of a renovation that added a room and expanded another room in the house. Our Peerless oil burner is only 5 years old. One option is to get a gas gun for the current oil burner, which our plumbing/heating contractor says should have enough capacity but 'it will be close.' The alternative is to replace the boiler with a slightly higher capacity gas furnace. Any suggestions?

Has a heatloss been done? That is the only way to determine the size of the boiler that is needed. It is also the only way to determine how much emitter you need in the addition. Why would you completely switch to forced air for a gas conversion?

ChrisJ

If the boiler is big enough now, why won't it be after the conversion?

SWEI

I'll just add that it's quite likely the existing boiler is itself oversized. Assuming the block is still in good shape, a gas gun can often be sized (down) and tuned to the heat loss, which can increase the efficiency of the boiler.

Steamhead

Is this a steam or hot-water system?

SWEI

Good point...

ChrisJ

Do boilers produce less output when converted with a gas gun?

Charlie from wmass

The efficiency is 2 percent lower with the same rated input btus with gas vs oil. So yes it can be lower. It often is a none issue as the boilers are usually slightly to grossly oversized. If this is the case they can be downfired to the required output rating and you gain back some efficiency points.

ChrisJ

2%?
What is that, 1000-2000 btu/h on the typical boiler?

Paul48

Has there been any mention of a chimney liner? If you add that to the equation, it might be time to look at a mod/con. It's an option, a great option, when handled by a highly competent HVAC contractor. Handled by a contractor that only matches the capacity of what is already in the house, it can be a nightmare.

I guess we need to clarify something......Is this hot air, water, or steam?

Robert O'Brien

If it's not steam, the smallest Peerless oil boiler is 3x larger than the average NYC area homes heat loss

Charlie from wmass

Also peerless says a. Gas conversion voids the warranty.

ChrisJ

Charlie from wmass said:

Also peerless says a. Gas conversion voids the warranty.

So void the warranty and if the boiler fails 5-20 years from now spend the money on a new one at that time. No?

Charlie from wmass

It is not my choice, every homeowner needs to weigh that for themselves. But if this is hot water Robert's point stands, the boiler is too big.

ChrisJ

Charlie from wmass said:

It is not my choice, every homeowner needs to weigh that for themselves. But if this is hot water Robert's point stands, the boiler is too big.

I don't know if anyone can say that without seeing a heatloss done on the house.

We don't even know what size it is.

Charlie from wmass

I can, I asked the magic 8 ball. Lol

njtommy

@ChrisJ too big is the size. How many times have we ever seen a house or at least posted on here being too small of a boiler. I can personally say 2 times in 12 years I've seen a system that was too small.

Tinman

I've seen plenty of undersized AC's but not any boiler that I can remember

Paul48

That's because guys won't admit when their unit is too small.

Charlie from wmass

Albany NY is the home of undersized steam boilers. Most of the problem boilers I see there are undersized if they are under 10 years old.
Has the OP answered iif it is steam or hot water?

ChrisJ

njtommy said:

@ChrisJ too big is the size. How many times have we ever seen a house or at least posted on here being too small of a boiler. I can personally say 2 times in 12 years I've seen a system that was too small.

My house had a Burnham V83 connected to 392sqft of radiation when I moved in.

Oddly enough, the V83 outputs something like 63,000 btu/h I think? Which is just about right for the house's heatloss.

Sadly, that's not how any of this works with steam.

jumper

My experiences in the seventies & eighties are like njtommy's. Generations ago local authorities ordered too big heating systems. Then in the eighties they insisted on marginally sized replacement boilers and furnaces for those over sized systems in the name of energy efficiency. Rarely a problem in Toronto where those design condition cold snaps don't last long. Other places can be different.

Robert O'Brien

ChrisJ said:

Charlie from wmass said:

It is not my choice, every homeowner needs to weigh that for themselves. But if this is hot water Robert's point stands, the boiler is too big.

I don't know if anyone can say that without seeing a heatloss done on the house.

We don't even know what size it is.

I've never seen an undersized hw boiler in 38 years. The smallest Peerless oil is 129K. I stand by my statement

Tim McElwain

What is the Make Model and Serial number of the existing boiler? Was a heat loss done when the oil boiler was replaced?

A gas conversion burner can if properly set up and the unit fired to its maximum design efficiency be equal to the oil gun if not a couple of percentage points above.

My experience (over 3,500 gas conversions in my career) on converting most Peerless boilers has always been good. I never worried about warranties as i picked up the warranty myself.

captainco

Yay Timmie!! A comment based on experience and confidence rather than opinion and insecurity. What Timmie says is absolutely solid.