Tankless Water Heater in Gas-Fired Steam Boiler

saikosis

I have a tankless coil insert for hot water in my oil-fired boiler and wanted to do the same with a new gas-fired boiler when I convert. I just had a contractor tell me that you can't do tankless with gas, but it looks like the Weil-McLain EG boilers support tankless with gas. Am I wrong? They definitely say the EG series does tankless, but is it only for propane? (Sorry if that's a dumb question.) I tried to call Weil-McLain to ask, but couldn't find a phone number. The contractor says he prefers Peerless, and it looks like the Series 63 do not support tankless, so maybe he's just not up on his Weil-McLain stuff.



I'd appreciate any comments. Thanks.

Dave in QCA

What ?

Tankless water coils don't care whether you're burning gas or oil. It just depends on whether the particular model of boiler is offered with the option.

You're looking at the WM EG-50. Here is the sales brochure. Tankless coil is offered as an option.



http://www.weil-mclain.com/en/assets/pdf/EG-Brochure-Series-5.pdf



Do you have confidence in your boiler man?

saikosis

Not a Lot of Confidence

I don't have a lot of confidence in any of the contractors so far. I just read We Got Steam Heat and have been reading and posting on here like a madman, so I know a little bit. Now I just need to find a real steam pro to put in a new boiler and help me sort out the problems in my system. I'm finding a lot of people who "do a lot of steam," but not a lot of people who don't sound like knuckleheads.

Dave in QCA

Find a Contractor

Have you checked under "find a contractor" on this site? Where are you located. Perhaps some of the other readers might have a suggestion.

saikosis

Yup

The guy who told me you couldn't do tankless with gas is listed on the Find a Contractor page. I just have to keep searching I guess. If anyone knows a real pro in Southeastern Massachusetts, I'd be eternally grateful.

JohnNY

Hold on.

Weil-McLain is the one boiler manufacturer who, albeit reluctantly, provides the means to install a tankless water heater in their atmospheric gas-steam boilers.

Even they know it's not a good production method for domestic hot water and a conversation with them will tell you that as a stand-alone product, they consider the tankless coil an option for "intermittent" or infrequent use of hot water.



If for some reason you're considering using a tankless coil to make your domestic hot water, then you need to think about what insulated storage tank you're going to pair it with to make it a sensible installation that works efficiently with steady, stable water temperatures. The old way of overheating the boiler and water and using a mixing valve in the hopes it doesn't scald the residents should no longer be on the table as an option.



Example of a storage tank here (but with a different hot water source). Same idea:

Dave in QCA

your favorite

John, what would you say is your favorite way to set up domestic hot water off of a steam boiler?



Myself, I have opted to not use the steam boiler at all. I have set up a lochinvar finned copper heater and a highly insulated AO Smith storage tank. But, this is a multifamily building.

JohnNY

Lots of options, as you know, Dave.

I don't mind using a heat exchanger with a steam boiler, be it immersed in the casting (tankless coil) or a immersed in a tank (indirect water heater).



Basically, what I mean is I always incorporate storage. It makes most sense.



Here in NYC, we don't often have the room or chimney capacity for multiple heat sources, so I do tend to combine the functions within a single fuel-burning appliance.

saikosis

You Lost Me

Sorry, I got a lost a bit there. Let me see if I understand. With a tankless coil, the heat from the boiler is used to directly heat the water that eventually comes out the tap, right? With indirect, the boiler heats something that in turn heats the water that comes out the tap. Is that true? Aside from what's being heated by the boiler, is the fundamental technology the same. That is, could I get hot water directly from the coil for now and then upgrade to indirect later by just piping it to a separate tank?



The tankless coil in my oil-fired boiler works fine for us now. There are only two adults and two small children in the house, so we rarely if ever have more than one hot tap running. It keeps up with a long, hot shower just fine. I'll admit that it does struggle with the bath tub. We generally can't get a nice hot bath going, but we do get kid-friendly warm water which works for us. Is there any reason to expect worse performance from a tankless coil in a new gas-fired boiled?

JohnNY

Your breakdown of the process is accurate.

The difference is that oil produces a hotter flame which translates to a higher concentration of energy in a smaller space. A similarly sized gas boiler is unlikely to produce a comparable result in hot water production in equal time (gallons per minute).



Heating domestic water through a boiler-immersed tankless coil consumes far more energy than what is realized at the outlet of the faucet. It's a black option in terms of efficiency except for during those rare times you're actually firing to make heat and hot water simultaneously. That goes for oil and gas-fired boilers.



I suspect the guy who came to your house that you found on this site knows all this and tried to steer you away from it.

saikosis

So What's My Best Option?

What's my best option for the short-term?



I have an oil-fired boiler with tankless hot water and a propane cooktop in the kitchen. I went down the path of switching to gas because I didn't like having two fuels to worry about. We use very little propane, so we pay a high price per gallon. Because the tank is leased (the previous owners set this up, not us), so we're tied to the company that owns the tank and can't shop around for better pricing. Also, my road is being repaved, which will put a five-year moratorium on any utility work that involves digging up the road. If I get everything installed by December 31, I qualify for a seven-year 0% loan from the state. With all that in mind, I figured now was a good time to make the switch.



I have until March to hook up to the new gas line otherwise I'll have to pay a $2500 installation fee. I could use oil for the winter, keep doing my research, and switch in the spring. I'd miss out on the 0% loan, but that's not necessarily a deal breaker. My big concern is that winter is coming and I've got a wife, toddler, and newborn to keep warm, so I at least want to have a plan, even if it's just "do nothing right now," so I can get some peace of mind and stop worrying about it.



Let's say I go with the Weil-McLain with the tankless option. I'll be making lots of steam this winter, so hot water should be covered, right? It'll be a little inefficient, and I'll maybe get less volume than I'm used to now, but I'll have something. Is the insert the same for tankless vs. indirect? In other words, once heating season is over, can I buy an indirect heater and just repipe the insert so that the hot water goes to it instead of to my taps? If so, does this sound like a reasonable path forward?



If I had all the time and money, what's the ideal solution? Boiler plus separate water heater? It's an old house, so I don't have a lot of floor space in the basement. It's also just a fairly small center chimney, so I don't know how much exhaust you can push up it. ChrisJ's basement and center chimney actually look a lot like mine:

https://plus.google.com/photos/101157864091065299849/albums/5765428421835656961?banner=pwa&authkey=CImUxIqv9436MQ

SWEI

Just tell the gas company this

that you plan to install the boiler, a tankless water heater, and a gas fireplace and perhaps barbeque.  That will assure you the right size line into the house.



Equipment decisions are now open for discussion.

BobC

Wet based boiler

Have you considered using a wet based boiler with a gas gun in it? A wet based steam boiler will be more efficient than any atmospheric steam boiler.  Both Smith and SlantFin make oil fired boilers that have been approved by the manufacturers to use the Carlin EZ-Gas. Also what make and model of oil fired boiler do you have? If it's in reasonable shape you might be able to mount an EZ-Gas on it, when the boiler does die you could just move the EZ-Gas over to a new boiler.



I had a Smith G8 and Ez-Gas installed last fall and it has saved me a lot of money compared to the old Burnham v75 oil fired boiler. The gas gun is noisy in some installations; mine initially had a loud rumble (louder than the v75 oil gun) to it but when I swapped in a smaller orifice to more closely match my EDR needs it quieted right down.



I don't think you will have any problem with hot water on a gas fired setup in the winter, in the summer you might have to raise the water level in a boiler to completely cover the hot water coil. In fact if your hot water needs are modest the more economical rout might be to use a standard 40 gallon gas hot water tank, They run pretty cheap if you don't use a lot of hot water. I use about 12 therms of gas a month in the summer on my gas hot water heater, it depends on how much hot water you use.



Bob

saikosis

The Line is In

The line is already in. When I applied, I told them it would be for heat, hot water, cooktop, grill, dryer, and swimming pool heater. Everything after the cooktop is fictional. I just wanted the biggest line they have, but I think they give everyone the same size.



If I don't start using gas within 180 days of when they put in the line, I have to pay a $5000 fee. I originally said it was $2500, but I went back and checked the contract and it's actually $5000.

saikosis

Wet Based?

What's a wet based boiler? I haven't heard that term before.



I have a Utica now. I don't have the model number handy, but I believe it's a Starfire. It was installed in 2006. We bought the house in 2011. We discovered a crack in the block a couple months later. Well, we discovered it was losing water and spewing steam up the chimney and a service guy actually found the crack. The warranty was technically no good because it only covered the original owner, but a Utica rep told me not to say anything and I ended up getting a new block for free. I had to pay a grand in labor though. It was a nice introduction to home ownership.



The current boiler is piped totally wrong. The risers and header are narrow copper, there's a radiator pipe directly off the header, the equalizer is goofy, and the Hartford Loop is wrong. The boiler is also a tad oversized, although that may have been the closest fit available at the time.



Anyway, Utica says this model can't be converted, but I know there are third-party burners available that do the job. A couple contractors said they wouldn't switch it because it wasn't supported by Utica. One guy said he'd switch it and even quoted me a number over the phone... even before I told him who made the boiler. He says "they're all the same."

BobC

wet based

Most residential gas fired steam boilers have a row of burners below a cast iron vessel, like a big tea kettle. A wet based boiler surrounds the fire with a water jacket instead of sitting below the "tea kettle". The wet based boiler gets more of the heat into the water because it has lower loses.



A gas gun in a wet based boiler works just like an oil gun but is a lot cheaper to run because natural gas is a lot less expensive than oil and a gas gun has much less excess air than an atmospheric boiler does; less excess air gives better efficiency.



Bob.