Boiler exchange

12 years ago

My dad has proposals from three contractors for oil-fired boiler conversion to gas. He is not seriously considering two offers from these contractors to replace the oil burner with a gas burner and leave the 55 YO Crane Sunnyday in place. That old soldier, in case you are not familiar, provides heat and DHW (with a coil). He is alone in the house most of the time with weekend and vacation time family visitors. He is in central NY. (There are lots of heating degree days there.) There are fin-tube radiators in three zones, one very small.

Two contractors proposed a Weil-Mcclain GV90+ Neither of these included an outdoor control. They are probably correct in their conclusion that dad will not live long enough to pay back the price in energy savings for that option. Are there other advantages to that kind of control that should be considered?

One with a PurPro 40 indirect water heater (Pro41Z140)
The other one with a Bradford White PowerStor 30 gallon indirect.

One of the above contractors also proposed a Baxi DuoTec (BAXLUNADUOTEC40KIT). Again, no outdoor reset.

A third contractor proposed a Rinnai E110C. Apparently, this comes with a outdoor reset as standard equipment.

I know that the combination boilers will not provide hot water as fast as the indirect heaters. I hope that they will match what he has now. There are some price differences, and there are differences in what will be done with the existing oil in the tank, buy back or give away.

What IÃ¯Â¿Â½d like are some comments on the operational differences in these boilers. (I see that the Baxi is a 7:1 whereas the Rinnai is 5:1.) In addition to that, any comments about reliability would be nice and any input about installation complications. I am having a hard time comparing the DHW output of the modulating boilers. The Baxi literature says that will make 3.9 gpm but give not temp differential to go with that. The Rinnai says 3.2 gpm at 75F delta.

There are things that I do not understand about the boilers. How are the Rinnai and Baxi able to handle a constant flow-through of oxygenated water while the Weil Mcclain is not? Is there a minimum water flow to activate water heating with these combination boilers? Does space heating output drop when DHW is made? The Rinnai installer says that he can go out the side of the house with flue gas, but the others say that they need to put pipe up the existing chimney due to window locations. Is there a difference with the Rinnai that dictates this?

Thanks for reading

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Comments (4)

jackfre
12 years ago
I know the Rinnai very well. You are correct on the hot water output of the 110. Yes, there is some delay in hot water but mostly that depends upon location of the equipment, location of faucets and hot water piping lay-out. The 110 does have a very robust outdoor reset control. As well it comes with the low loss header. The LLH provides the primary secondary piping. It has a heavy stainless steel HX. It can be vented side wall and the clearance to a door or window is 12". It can vent with either the concentric poly propylene pipe or with 3" PVC. The adapters are provided. The 110 as you know is a Combi boiler and has a 3 way valve internal to the unit that senses hot water flow and diverts the boiler output to the DHW. That is called DHW priority.

I am definitely biased to the Rinnai. They have a much stronger support base as a company. The first time I fired a 110 up I had a bunch of the Boston Gas Utility folks with me. On a first time start-up, with an audience, I was nervous. I turned it on and waited for its pre-purge and self check and waited and waited. I couldn't hear anything. I didn't think it was running. Finally one of the guys grabbed one of the pipes and let go in a hurry as it was hot. I then looked up into the left side view port and saw the flame on the ceramic burner. Relief! Very quiet in operation.
jimct01
12 years ago
I can't offer advice on the specific device but I can say I replaced my ancient Sunnyday with a 85% AFUE oil boiler (Solaia/BASI) and cut my oil consumption 35%. Gas not available in my area. Getting rid of that dinosaur and switching to gas should save your dad a ton of money.
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ionized_gw
Original Author
12 years ago
Thanks for the encouragement. I guess that a big chunk of your 35% is due to the end of a constantly-hot boiler 24/7/365. I do have some concerns about possible condensation in that part of dad's basement since it will be much cooler. We've decided that there is really no point in worrying much about it until we see a problem,
monsim
11 years ago
I had a plumber install a Rinnai E110C in my house(built in 1915,I live in Massachusetts) in September of 2014. So far I am very happy with it. The time it takes to get water my shower upstairs(about a 30 foot run from the boiler) is about 10 seconds in the summer and maybe 15 seconds in the winter. Ground water temp in my area is about 52 degrees. However there were a few issues that I experienced. First, I had a concentric intake/exhaust pipe installed out the side of the house. When it would rain, water(the rain) would get into the intake portion of the tube(the outer pipe) and make its way back into the boiler casing and splash around and condense at the bottom of the unit. This is something you don't want to happen as the electronics are housed here. The pipe outside the house was positioned in the corner of where two porches on the house meet and when we would have a rainstorm this was a turbulent side of the house. I eventually had the plumber reroute the intake/exhaust to a two pipe(separate pipes and at an added cost of $800.00 to me) system and on a flat wall in a different direction. Problem solved.

My Rinnai E110C is positioned where the oil tank was. I had put speedi dry down where the tank was and right under the two pipes for hot water heating and return at various times There were moisture spots about 5 or 6 inches in diameter. Putting my hand on the pipes leading into the low loss header, my hand was wet with moisture - condensation. The low loss header itself is insulated with stiff Styrofoam. Just today I put insulation on those pipes and hopefully that will solve the problem.