Converting from oil to gas heat

9 years ago

Hi. We live in an approximately 80 year old brick home a block from the ocean in South Jersey. We have oil heat and have a tight utility room that houses the boiler and hot water heater as well as washer/dryer. There are only 2 people living in the house most of the time, but as many as 8 a few times a year. The house is brick and approximately 2000+ sq. feet. There are 3 1/2 bathrooms.

We want to switch from oil to gas to reduce the monthly bill and so we can get a gas stove. There is no problem getting gas to the house, and we presently have an above ground oil tank after having 2 underground tanks removed. The question is what to get instead of the present setup. We have received 3 quotes. 2 of them proposed a combination boiler/tankless water heater. We like the idea of that because it minimizes how much space the units will take up. One proposed a Bosch combination heat and domestic hot water wall hung high efficiency boiler with a capacity of 151,000 btus and AFUE rating up to 95% for $14,425. The other proposed a Quietside S-Line series with a capacity of 160,000 btus and AFUE rating up to 92% for $12,700. Those quotes included removal of the oil tank and all labor, materials, and permits.

The quote we received today suggested a Weil McLain boiler with 125,000 btus and AFUE rating up to 97% with a separate tankless Rinnai 7.5 gpm for $8,995. This quote came from someone who was not sold on the combo units and did not want us to be a guinea pig. His charge did not include removal of the oil tank.

We want to maximize the space in the utility room so we can add some storage. We do not want to do that at the expense of getting a lousy setup though. What we like about the current setup is that we can have all the showers, the dishwasher, and washing machine going at the same time and still have plenty of hot water. We understand that will not be possible, at least with the combination units. We would appreciate any feedback on the combination units versus separate tankless water heater and boiler. If we do decide to go with the combination unit, any thoughts or experiences with the Bosch versus the Quietside for the proposed prices would be helpful.

Thank you.

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Comments (4)

mike_home
9 years ago
You are making a good move by switching to gas. The savings will be significant.

The first priority is sizing the boiler correctly. Has any of these contractors performed a heating load calculation? I realize a 80 year old house may not have the best insulation in exterior walls, but I find it hard to believe you need 160,000 BTUs! Even the 125,000 BTU seems large. Are these contractors replacing the boiler size that already exists?

You have to decide what is most important to you. A combination unit takes up the least amount of space, but is more expensive. It may be difficult to find someone who is expert in installing these units.

A separate tankless unit is a good option, but you will not be able to run three showers at the same time. A separate 40 or 50 gallon conventional hot water heater would be the least expensive and allow you to take showers at the same time. It takes up more floor space, but depending on the layout it may not have much impact on the overall space.
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jackfre
9 years ago
Actually, Mike, he could run 3showers with the tankless. An RU 98 is a 199,000 btu, .95EF unit that at a 70* rise makes, I think it is, 5.8 gal. My 2.5 gal shower head uses 2.1 gal hot and .4 gal cold to make my 2.5 gal hot shower. By using the 2.5 gal head in the master and either 2 or 1.5 gal shower heads in the other baths it will fall within the capacity. The referenced RL75 (180,000btu), which I installed in my house, will make 4.3 gal at a 70* rise.

This hi occupancy type situation is where tankless really shine. A few years ago we had a couple getting married and their young friends were having problems with the costs of hotels. We opened the house and had about 16 kids in for the weekend. Everyone took as long a shower as they wanted, showered sequentially (continuously) and we never ran out of hot water.
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mike_home
9 years ago
The key would be the shower heads need to be the new low flow rate type. The flow rate would be a function of the water pressure. The water pressure may not be enough for three showers, but should be adequate for two.
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allisonj33
Original Author
9 years ago
Thanks for your input. I looked up the square footage, and it is closer to 3100 square feet. We are replacing a 131,000 btu burner. The low flow showerheads were recommended by the company suggesting the Bosch and would be added to the showers that do not already have it as part of the project. The house is brick, and most of the walls are plaster. They have very little insulation. We have not done a heating load calculation.

The utility room is about 94" x 94". Our present hot water heater is elevated 4 feet above ground and is about 4 feet high and sticks out about 2.5 feet. So, it takes up significant space.

Do those prices seem reasonable? Any recommendations on the Bosch versus Quietside if we decide on the combo unit?
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Converting from oil to gas heat

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Converting from oil to gas heat

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mike_home

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