Oil Burner Question

sgall

Hi I am new to this great site.  We are in the process of converting from oil to gas.  I am planning on doing a comprehensive heat loss but I was just curious about our old oil boiler.  It was made by The National Radiator Company and it says it is a 300 series.   It doesn't mention the size in BTUs directly but it says "Oil 3.75 gals per hr."  Can i just multiply 139k x 3.75 to get a size figure or am i missing something?  thanks

icesailor

Boiler Rating:

Regardless of the rating on the old boiler, you need an accurate heat loss calculation FOR THE BUILDING and install the heat source based on this figure.

The boiler you have now is probably older than dirt. I'm sure that improvements to heat loss have been added since installation and the boiler and heat system were over sized from the beginning. 

If anyone tries to sell you a boiler based on the old boiler and radiation, and not the heat loss of the building, call someone else.

Within the next five years, gas will be priced at the same per BTU ad oil. When the gas companies and commodity speculators get done converting all the oil power plants to gas, there will be a huge drop in price. Only speculation is keeping oil, Liquefied Petroleum Gas and gasoline as high as it is. Think Enron. Enron bankrupted California and other western states before they themselves went bankrupt, wiping out the savings of thousands of employees.

Rod

Boiler Size

Hi- Is your system steam or hot water?  3.75 gallons per hour is a lot of fuel! Either you have a huge house or your burner is very inefficient! I have a 3 story house in rural Maine with practically no  insulation and I use only 1.50 gallons per hour on my steam system.

- Rod

sgall

System

is forced hot water and the house is 3 stories, 3700 square feet with single pane windows, old storms and some insulation.  We bought the place on Jan. 31st and have spent over $4k on oil.

sgall

System

is forced hot water and the house is 3 stories, 3700 square feet with single pane windows, old storms and some insulation.  We bought the place on Jan. 31st and have spent over $4k on oil.

sgall

thanks

We are doing the heat loss but as I mentioned I am just curious about the old system.  My take on the world energy situation is quite different from yours.

Rod

Hot Water

It sounds as though there are a lot of things you can do to improve the efficiency of your system. You might want to look in the Contractor section at the top of the page and see if someone is located close to you. There are a lot of very good heating guys listed there.

Also check in the "Resources" and "Systems" sections at the top of the page as there is a lot of good info listed there. Check out terms like Mod Cons (Modulating /Condensing boilers), outdoor reset and TRVs.  Aside from that, keep in mind the "biggest bang for the buck" is improving your home's insulation.  I'm a steam system homeowner so my experience with HW is rather limited. Keep asking questions and learning. There are a lot of really top notch HW people, pros and homeowners, who frequent this board and will be glad to help you out.

- Rod

Jean-David Beyer

3.75 gallons per hour is a lot of fuel!

My house, built in 1950, is 2 stories and 1100 square feet; it needs about 30,000 BTU/hour when it is 0F outside. When I had oil heat, I had a 0.5 gallon per hour nozzle in it and that was always enough heat. If yours is triple the area, perhaps you would need 1.5 gallons per hour. I would mistrust a rough guess of heat loss by floor area, but a heat loss calculation will tell you.

sgall

Thanks Rod

I have been researching as much as I can but still have a ways to go.  If I am thinking about this correctly there will be 3 boiler specific factors that will effect the heating savings going forward.  The first will be that NG is currently less expensive than oil.  2nd is the efficiency pick up from an old inefficient system to HE mod/con with ODR etc.  And the third will be correcting what looks to be a very oversized system.  Basically this is what prompted my initial question - I am trying to get a rough idea of what the savings will be.  The efficiency and NG vs. oil pieces are easy enough to figure but don't know about the oversized calc.

Steamhead

That's a "Heat Extractor", model A-306

you can see its ratings here:



http://www.heatinghelp.com/files/articles/947/190.pdf



This was probably a replacement for an old, oversized coal boiler and they just put the same size in. The heat-loss calculation will tell you for sure. If I'm right, the high fuel consumption is due to the oversized boiler more than the fact that you're burning oil.



Another thing- the Heat Extractor series were three-pass, all-fuel, dry-base units. When burning oil, it helped a lot if baffles were placed in the boiler's flue passages to slow down the hot flue gases and make them wipe the cast-iron better. This required some know-how, though, and I'd be willing to bet yours doesn't have any baffles- oil companies don't like them because they make the unit use less fuel.



Post the results of the calculation when you finish.

Rod

Measuring Installed Radiation

Again I must state my area of knowledge is steam rather than Hot Water.With Hot water determining heat loss is the thing as Hot Water can be varied in temperature (Mod Con)  to match the existing heat loss at a particular time interval where steam is 212 degrees + all the time and that's what you work with.

 I'm assuming you have old cast iron radiators . If so, you can use the attached chart and figure out the installed radiation of each radiator in each individual room. Note the chart uses 190 water temp for HW in the conversion factor rather than a 180 degree temp which i believe is now used as a standard but this should get you in the ball park so to speak. You might want to take a look at the Burnham Heating Helper http://usboiler.burnhamparts.com/assets/docs/heating-helper-2010.pdf as it has a lot of tables and formulas which might be of help to you.

- Rod

sgall

thanks

From what I have gathered so far I would have to agree that it is probably mostly due to the oversize issue.  A plumber did measure the radiators and came up with 280k (76 BTU per sq ft.) which still seems way too big.  I have done a few initial passes on the heat loss and come up with anywhere from 102k - 137k (Boston area).  I plan on doing a comprehensive one over the weekend.  I will keep you all posted and thanks again.

Charlie from wmass

Measuring the radiators or checking the fuel rate of fire

both are good ways for fuel companies to size boilers as it makes the consumer pay out their ears for heat. This is what makes free boilers possible. What program or method are you using for your heat loss?

sgall

heat loss

At first I thought I might pay someone to come out and do it but that seemed very expensive.  I think I am going to gather all the data, plug it into the provided spreadsheet and have comfortcalc.com do it.  What I like about it is they seem to require a lot more data which can only help.   it is fairly reasonable.  I have done a few rough estimate ones using slantfin and another spreadsheet that I can't remember where I found it.  They both came in fairly close to each other.

sgall

Heat loss results

hi,

I got the heat loss back today and it came in at 79,500 so way lower than the old boiler and the existing radiation.  I am still researching and learning but I am leaning towards the Burnham Alpine at this point which is available at a discount from National Grid.