Replacing 30 year old Oil Boiler

If the energy audit includes a heat load calculation that would give you some useful info.

Next step is to measure how many feet of fin tube

Times 550 btu/ ft. See how it matches the heatload number

In some cases the boiler can run much lower than 180 f.. The lower the operating temperature the more efficient the boiler will operate

With outdoor reset control , much of the season a mod con will modulate down to a lower firing rate. This saves fuel $$ and increases comfort with less boiler cycles.

Plenty of homeowners learn how to service and clean their mid con boilers.

@jrunks1221 , what boiler do you have now?

Why convert to LP?

Compaire the cost per BTU

Fuel Comparison Calculator for Home Heating | Coalpail.com

It could be a knee-jerk reaction to the current price of oil which is really high. But in the 30 years I owned my home and my commercial building, the oil costs at home were a lot cheaper than my commercial building on NG. Propane in CT is even more expensive than street gas.

I expect the cost of heating oil will be below $3 by fall.

Another concern is with 5 zones a buffer tank may be needed.

The idea of having only one fuel source can make sense—but only if that fuel source is affordable.

You can convert nearly everything in your home to run on electricity. It’s already available, and it can power a wide range of systems. Fireplaces can be replaced with electric units that simulate a flame and provide heat. Cooking, space heating with an electric boiler, and even clothes drying can all be done with electricity. In theory, reducing your home to a single energy source sounds simple and efficient.

However, there’s a major drawback: electricity is typically one of the most expensive ways to produce heat. You may eliminate a $1,000 fuel oil bill, only to find that heating the same space with electricity costs $3,000. That makes it a poor financial decision—especially if you’ve invested five figures in a new electric heating system that ends up costing significantly more to operate over the next 10 to 30 years.

Applying the same logic to LP gas, switching from an existing oil system may not make financial sense either. In many areas, the delivered cost of propane per gallon is equal to—or higher than—the cost of fuel oil. At the same time, propane contains less energy per gallon.

• #2 heating oil: ~138,500–140,000 BTU per gallon
• LP gas (propane): ~91,500 BTU per gallon

So even if the price per gallon is similar, you are getting fewer BTUs per dollar with propane.

As a rough comparison, if fuel oil costs $3.50 per gallon, propane would need to be priced at under about $2.50 per gallon to provide a similar cost per unit of heat, even when accounting for differences in equipment efficiency. Call a few local LP gas companies to find out how much LP is per gallon when you use it fro a generator, fireplace, clothes dryer, cooking, heating and hot water. that should get you their lowest price since you will be a frequent buyer. I bet you it is still going to be higher that your #2 heating oil.

The bottom line: before switching fuel sources, it’s critical to compare both the installation cost and the long-term operating cost. In many cases, keeping a properly functioning oil system may be the more economical choice.

The noisy startup on your oil burner is an easy fix for someone that understands oil burners. Your burner needs a good tune up and it may even use less fuel that you are currently using after proper maintenance. You just need to find the right oil burner tech.

I am very familliar with the Weil McLain P-WGO-4. that means that you DO NOT have a tankless water heater inside the boiler so the tank next to the heater is an indirect.

27 Gallons is an odd size tank. I have a feeling that you have a 30 gallon indirect that has 27 potable water capacity with a heat exchanger that holds about 3 gallons of water. Total 30. Can you post a photo of your boiler and your water tank so we can help you better understand your system.

Now there is a possibility that a 30 gallon tank may not keep up with your DHW demand with your family of four.  But there also is a possibility that with a very low cost set of adjustments you can have a system that provides more than enough DHW for your needs and you don't need to purchase any new, expensive equipment.  Or at the worst case, purchase less than half of the cost of an entire new LP gas heating system and get where you need to be with lower operating costs.

If I were to make an educated guess, that 27-gallon tank and the P-WGO-4 were likely installed at the same time years ago. You most likely have a Weil-McLain PLUS-30 indirect tank, similar to the one illustrated in the first column of the sizing guide.

With proper setup, you can achieve a first-hour rating of up to 230 gallons of hot water.

The first step is to set the P-WGO-4 high limit to 200°F. Next, make sure the water heater zone is set to priority. This means the boiler will temporarily stop space heating whenever there is a call for domestic hot water (DHW), allowing all available heat to be directed to the indirect tank.

Once that is verified, the remaining step is to ensure you are not exceeding approximately 3.8 gallons per minute when taking back-to-back showers. At that flow rate, it is not possible to exceed 230 gallons of hot water within a given hour. The math says so!

The reason I know this is possible is because the P-WGO-4, when set up for peak performance, can deliver a NET output of approximately 126,000 BTU per hour. This rating already accounts for a 15% piping and pickup factor based on an average heating system.

Since your water heater is located very close to the boiler, the actual piping losses are significantly less than 15%. As a result, you are effectively delivering more than 130,000 BTU from the boiler to the water heater.

The numbers support this. All that’s needed is a properly set up oil burner—one that operates with smooth, quiet starts and clean, soot-free combustion. This requires the use of a combustion analyzer and skilled workmanship to ensure the system is operating at its full potential.

@jrunks1221 , how about a pic of your hot-water tank?

I believe the smallest BoilerMate was the 41 gallon