# converting propane boiler to natural gas



## drewhart (Jul 13, 2008)

is it just a matter of putting a different valve on?


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## hvaclover (Oct 2, 2008)

How do you know the boiler is the right size for your home and if it's in working order?

Is it steam or hot water?


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## drewhart (Jul 13, 2008)

it is hot water. i dont know if its the right size. the house is 1900 sq.ft and the boiler is a weil mclain 140,000 btu. will this suffice? i just need some heat! this one i can get a good deal on, i just dont want to spend 3,000 on a new one.


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## hvaclover (Oct 2, 2008)

seems way over sized to me.


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## drewhart (Jul 13, 2008)

is it ok to use one way oversized?
seems to me i could run it low which would preserve it's usefull life. 
this seems better that running one high which is too small right?
so what is involved in switching to natural gas?


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## beenthere (Oct 11, 2008)

Proper sized orfices, gas valve and or spring, new burners on some models.

Also need a Manometer.

Takes the same water temp weather the boiler is over or undersized.

If the the boiler holds more water then the current one, the you also increase its standby lost, increasing how much more gas you will use.
Also, if its larger then the old boiler(BTU wise) it will need more combustion air, meaning it draws more fresh air into the house. Which you have to pay to reheat.

Your chimney may not be able to handle the larger boiler.

Attempting to derate a boilers input, can cause condensate troubles in both the boiler and chimney.

Improper conversions have caused more then one fire.
And way too many CO posionings.


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## hvaclover (Oct 2, 2008)

Been correct me if I am wrong: Derating in excess of 20% will definitely cause condensation. For a 1900 sqft home you don't even need 100k, no?

So wouldn't derating this boiler be a very chancy since the amount of reduction far exceeds 20%?:huh:


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## beenthere (Oct 11, 2008)

Some units have problems if you try even 10%.

Might only need 80,000 for it.


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## Gary_602z (Nov 15, 2008)

I am not an HVAC tech nor do I play one on TV!:laughing: But wouldn't the type of house,insulation ,windows and geographic area come into play?

Gary


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## drewhart (Jul 13, 2008)

its a stucco house in cleveland ohio. the upstairs 4 bedrooms have been framed-in with insulation. downstairs is the original stucco/plaster walls with no insulation. all new windows up, all old windows down. i just read today on the boiler that it is 131,250 btu. it doesnt indicate whether thats input or output. there is a rating called "water sq. ft" of which it says 700. the one i want to put in here has a btu rating of 140,000.


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## JohnH1 (Jan 9, 2009)

Think about why you are getting this boiler for such a deal. Someone els removed it for some reason. That is a lot of work to install a used boiler and then have problems. If not a leak.


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## drewhart (Jul 13, 2008)

of the two i am trying to decide betweem, one was replaced because they invested in a new high efficiency boiler, the other because they switched over to furnace heat. before i buy it, i want to attach a fitting so i can compress air into it to see if it leaks. is this a viable test?


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## beenthere (Oct 11, 2008)

Gary_602z said:


> I am not an HVAC tech nor do I play one on TV!:laughing: But wouldn't the type of house,insulation ,windows and geographic area come into play?
> 
> Gary


Which is why I said "might" only need 80,000.


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## yuri (Nov 29, 2008)

NO! Boilers have to be heated up and full of water to see if they leak. It may lose air pressure but hold water when the sections expand. Boilers are tested with hydrostatic (water pressure).In my area there is no such thing as DIY major furnace repairs/conversions as you have to take out a permit/be licensed etc for safety and liability and insurance co. reasons. Beware if something goes wrong the fire inspector and insurance company will hang you by your neck/lawsuits etc etc.


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## JohnH1 (Jan 9, 2009)

drewhart said:


> of the two i am trying to decide betweem, one was replaced because they invested in a new high efficiency boiler, the other because they switched over to furnace heat. before i buy it, i want to attach a fitting so i can compress air into it to see if it leaks. is this a viable test?


That will tell you if it holds water not anything about the controls or safetys.
Kinda like a car engine. The block may not be cracked but what kind of conditions was it subjected to. It may work out great for you just saying buyer beware. You have no one to hold liable if a problem arises. I personally dont belive in taking the risk with used equipment.


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## beenthere (Oct 11, 2008)

drewhart said:


> of the two i am trying to decide betweem, one was replaced because they invested in a new high efficiency boiler, the other because they switched over to furnace heat. before i buy it, i want to attach a fitting so i can compress air into it to see if it leaks. is this a viable test?


Yes, and no.

The proper air pressure test, is not safe to do.

Keep it under the relief valve pressure setting.

Some boilers, after they have been used for a while, and then set dry, you can blow the seal out, when you pressurize them.


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## hvaclover (Oct 2, 2008)

Gary_602z said:


> I am not an HVAC tech nor do I play one on TV!:laughing: But wouldn't the type of house,insulation ,windows and geographic area come into play?
> 
> Gary


With 1900 sq ft He could keep the doors open and that boiler would still maintain temp it's so big.


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## JohnH1 (Jan 9, 2009)

hvaclover said:


> With 1900 sq ft He could keep the doors open and that boiler would still maintain temp it's so big.


Yah Leave the door open it is a built in snow melt system for the front porch.:thumbsup:


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## Dr Heat (Jan 14, 2009)

First do not do this yourself Installing a boiler is not connect the pipes and pray for no leaks.

As to the size. Over sized boilers are not the same as over sized furnaces. The biggest issue is will the flue and combustion air be sufficient? 

As to testing for cracks no real way on an old boiler you need heat and pressure and water going through the tubes.

If the boiler has set for a long time 3 or more years Rust will be an issue. 

The conversion is simple change the spuds the regulator spring possibly the burners. Then set the gas pressure. Getting the kit would be a trick. Lets say they still make the kit or someone has one how will you buy it. No responsible supply house will sell it to you. I hope.

I have done this for 30 years I would walk you through most any job but this is past DIY you might get a tech who would be willing to let you work with him and save a few Benjamins :thumbup:


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## drewhart (Jul 13, 2008)

i have a friend who has a pipe fitter friend that helped him put in a new boiler. if i get a boiler that is too big, asside from the flue issue, would it work? can it burned turned down so i dont have to keep the doors open? i would love to buy a brand new boiler and have it proffesionally installed, but as you know, the budget is limited. i just want something to creat somekind of heat safely. i can get this boiler for about $200. i heard i will need a new valve because propane is under more pressure than natural gas, so the valve opening is smaller. how do i know if i need a new burner? and where is the spring assembly?


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## drewhart (Jul 13, 2008)

http://cleveland.craigslist.org/for/976534135.html here is a link to the boiler that i want.


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## drewhart (Jul 13, 2008)

http://columbus.craigslist.org/for/963085052.html

this is the other one i am thinking about. the guy said him and his wife were out of town and the electricity went out. somehow the power to the boiler was cut off. when they came home, some of the baseboard heaters pipes burst, his wife said "i hate radiant heat, put in a furnace!" so thats why he is getting rid of this one. do you think the cold frooze anything in the boiler? im guessing it was in the basement which should be the warmest area.


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## JohnH1 (Jan 9, 2009)

drewhart said:


> http://columbus.craigslist.org/for/963085052.html
> 
> this is the other one i am thinking about. the guy said him and his wife were out of town and the electricity went out. somehow the power to the boiler was cut off. when they came home, some of the baseboard heaters pipes burst, his wife said "i hate radiant heat, put in a furnace!" so thats why he is getting rid of this one. do you think the cold frooze anything in the boiler? im guessing it was in the basement which should be the warmest area.


Freez up This boiler is a risk right off the bat could have been frozen.


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## JohnH1 (Jan 9, 2009)

drewhart said:


> http://cleveland.craigslist.org/for/976534135.html here is a link to the boiler that i want.


The burners look very rusty on this one make sure it was not in a flood.


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## beenthere (Oct 11, 2008)

That Valiant, is rusting out. Look at it.

The WM is an old reliable 60 year old design(design, not that unit). Gas hog.

Actually, they both gas hogs.

Flip a quarter to see which one you want.


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