Should I stick with tankless coil?
Comments
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Either run an indirect off of the boiler or add a separate water heater. Keeping the boiler hot 24/7 year round for the tankless is expensive. There are ways to run the indirect directly off of the boiler water below the water line, using the indirect as a hx for a conventional indirect coil or to use the indirect to heat the potable water with a circulating pump and a storage tank. If you use the boiler as a heat source, make sure you make the indirect large enough that the boiler runs infrequently under small loads or that will really eat in to the efficiency of the system.
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Some people here seem to love the idea of keeping a boiler hot in the summer to heat a few gallons of DHW but the mere idea of it makes me convulse.
Any standalone water heater would be better. Gas, or even traditional electric. But I recommend a heat pump water heater which is nearly free to run and often has state incentives available.NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el
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Generally a coil is not as efficient (without a storage tank) vs a stand alone water heater. The coil is sized based on the boiler size so smaller boiler will have less gpm vs larger.
Having said that if you are in an area like me where the boiler runs 6 months a year a coil is actually pretty efficient since if timed properly your hot water needs are "free" while boiler is making radiator steam. In 6 off months of non heating a coil is more wasteful but a payback on ROI for a standalone will be years out if like my case. So I stuck with the coil. I use approx $20-25 worth of natural gas/month in summer months including cook stove and boiler coil, so a standalone does not make economic sense for me, a wall hung will never pay back. Even a storage tank will be slow on ROI. Another downside of coil is if/when they fail later in the boilers life they can be impossible to remove without snapping the bolts or causing other issues. My last one went 23 year which surprised me, it was very crusty when removed from the boiler though!1 -
I will add it's nice for them to be separate so that if your boiler fails at least you still have hot water and vice versa
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el1 -
Paul, have you had a heat pump WH for some time?
How about the outcome...enough HW for how many.....cost of operation?
ROI?0 -
as a homeowner the last thing I want is a tankless coil . Running a boiler 24x7 to keep water hot wasteful and at todays fuel prices even more so. My house came with a tankless coil in a circa 1960 oil fired hot water boiler. The coil clogged soon after I moved in. I installed a stand-alone oil fired water heater (electricity has always been expensive in the Northeast). When I replaced the boiler later on with a 3 pass cast iron oil fired (natural gas was not option at the time) and I replace the water heater with an indirect 30 gallon water heater. You can’t run out of hot water, the 3 pass boiler is easy to clean and keep clean and I cut my oil consumption 33%. I would still opt for a 3 pass boiler (they don’t take tankless coils) which only runs when there is a demand for heat ) but in this day I would look at heat pump
water heaters. There is no way I would ever install a tankless coil.
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Tankless coil in an oil fired boiler is the worst idea ever. In the 1940s and 50s Levitt used them because they were less expensive to install one oil burner that does 2 jobs. Saved the builder money 1 time. Cost the homeowner in wasted fuel for years.
Oil dealers were happy with the idea of selling some oil in the summer months. If you didn't use oil for hot water then you would probably use an electric water heater. Can't sell any oil for an electric water heater. Even though a tankless coil is probably less expensive to operate than a stand alone electric water heater... there are more cost efficient options.
Proper installation of an indirect water tank off of a high efficiency boiler will pay for the additional install expense in as little as 5 to 8 years. The life expectancy of the equipment is over 20 years.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Does the Mega Steam offer a tankless coil?1
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Ugh, i wish it was an easy choice! It seems like it would be better for the boiler to not have a tankless coil, and get an indirect instead. I have thought about just getting a heat pump water heater, too. They offer rebates now around 600 bucks for a 55 gallon. I’ll look into what the cost difference is between these two options. Thanks.0
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I've had mine for I think over two years now, so not too long, but I have a 5 years parts and labor warrantee on it so I'll let you know after that!JUGHNE said:Paul, have you had a heat pump WH for some time?
How about the outcome...enough HW for how many.....cost of operation?
ROI?
They come in 50 and 80 gallon and you can set them to use resistive for faster recovery if you find you need it. The cost of operation is amazingly cheap. 25 cents per day here, but everyone's usage is different.NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
ethicalpaul said:
I've had mine for I think over two years now, so not too long, but I have a 5 years parts and labor warrantee on it so I'll let you know after that!
They come in 50 and 80 gallon and you can set them to use resistive for faster recovery if you find you need it. The cost of operation is amazingly cheap. 25 cents per day here, but everyone's usage is different.
Will they honor that warranty for yours? Or are you SOL like many DIY?Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Have you seen many examples of actual denial of claims for DIY installs when the product was at fault rather than the install? I have had far more problems with supply houses than manufacturers.1
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Well they sell it through Home Depot so I'm pretty sure they'll honor it if need be
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
No, I haven't tried.mattmia2 said:Have you seen many examples of actual denial of claims for DIY installs when the product was at fault rather than the install? I have had far more problems with supply houses than manufacturers.
But my gut tells me we're on our own.Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Free hot water from a crusty tankless coil in a boiler. Really?nde said:Generally a coil is not as efficient (without a storage tank) vs a stand alone water heater. The coil is sized based on the boiler size so smaller boiler will have less gpm vs larger.
Having said that if you are in an area like me where the boiler runs 6 months a year a coil is actually pretty efficient since if timed properly your hot water needs are "free" while boiler is making radiator steam. In 6 off months of non heating a coil is more wasteful but a payback on ROI for a standalone will be years out if like my case. So I stuck with the coil. I use approx $20-25 worth of natural gas/month in summer months including cook stove and boiler coil, so a standalone does not make economic sense for me, a wall hung will never pay back. Even a storage tank will be slow on ROI. Another downside of coil is if/when they fail later in the boilers life they can be impossible to remove without snapping the bolts or causing other issues. My last one went 23 year which surprised me, it was very crusty when removed from the boiler though!
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
One thing needs to be mentioned, maybe two. Water quality. Mineral content AND chlorides wreak havoc with water heating equipment, boilers, tankless coils, gas tankless heaters, tank water heaters of all kinds including stainless steel.
Best to have the water checked for minerals like calcium, manganese and chlorides. In Manchester, NH I have seen a multitude of issues resulting in chlorides massing with minerals and clogging mixing valves, T&P valves and fouling tankless coils.
The short fix is a stepped, 20/5 micron particulate filter, a large carbon filter and a descaling cartridge with by-pass valving. Seems to work, if you can get the customer to believe it. Many won't due to cost, saying something like, "It's been this way for 40 years, not going to change it now" or "that's a lot of money".
On the tankless coil attachment, The mating surfaces need to be sanded clean to bare metal, threaded holes chased with a tap and cleared. I use stainless steel studs, nuts and washers with Never Seize and thick Gator Hyde, EPDM, gasketing. Also, a very thin layer of silicone applied to both sides, allowed to cure for 10 minutes makes for a very durable seal, and easy to remove later. Fasteners must be re-torqued every year. (Yeah right!)2 -
That is what I was told when I worked for the oil company. "Where else could you get FREE hot water for 6 months, then from us, your dependable oil dealer!" If you put in a gas or electric water heater, then you will have a higher gas or electric bill for hot water all 12 months.hot_rod said:
Free hot water from a crusty tankless coil in a boiler. Really?
That is what my father told me. and he would not lie to his favorite son!Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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not me,,i have a coil and it works great,i just turn off the boiler with a switch so it only runs when we need hot water,,takes about 5 minutes once the boiler is up to temp,, i have all the hot water i need for a shower,,also i clean the coil every couple of years,thats makes a difference,,everyone that bashes a domestic coil don't know what there talking about,you just have to know how to use it
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I don't agree for the simple reason that not everyone takes the time to turn off the switch in the summer, and only turn it on for the few minutes it takes to shower. The vast majority of boilers with tankless coil water heaters are left turned on 24/7.
Kudos to @burnout for being the exception.
My understanding of common water heaters and the cost to operate them.
- Electric water heaters are 100% efficient but the fuel is rather expensive compared to the alternative fuels. They are not connected to a vent so the stored heat in that tank will stay there longer.
- Gas Automatic water heaters for the most part are connected to a vent (like a chimney) allowing for constant movement of air thru the heat exchanger that can transfer stored heat in the tank to that moving air. So in my opinion, they are less desirable than a storage tank that is not connected to a vent. The fact that natural gas and in some cases propane costs so much less. That makes the down time loss is more desirable than the higher cost electric fuel
- Oil fired water heaters also are connected to vents and therefore are less desirable than a tank that is not connected to a vent So the same as a Gas Automatic.
- A coil in a heating boiler used for DHW is connected to just about the most inefficient system. No matter how efficient your burners are (Oil or Gas) the boiler will be set at a higher temperature by design, than the actual water temperature desired at the shower. That makes the temperature difference between the air that flows thru the boiler to the chimney during the down time much lower than the water temperature. More heat will transfer from the boiler to those passing air currents so more heat will be lost up the chimney. If you happen to have an inefficient burner connected to that boiler, then you have a real fuel wasting machine.
- The best water heating system is to use the most efficient heating boiler available for heating your home. That will have a very high recovery rate when connected to an indirect water tank. (much higher than the burners that come with Gas Automatic water heaters). Now by using the super high efficient burner system to transfer heated water to the indirect tank. When that tank is satisfied and there is no longer a call for hot water, the burner in the super efficient boiler will stop heating the water. Since the DHW storage tank is not connected to a tank, there is no heat transfer to the vent from the tank. That tank, if no hot water is used because everyone is at work or sleeping for hours, will not need the burner to run for as long as 20 hours. That means that when the boiler cools off as a result of being connected to a vent, the burner does not need to turn back on to maintain a higher temperature for DHW as it would with a tankless coil.
- The most efficient water heating systems are instant tankless water heaters. There is no stand by loss which is the largest waste of energy. No tank to get cold when no one is using hot water. There are two major problems with tankless water heaters
- They seem to make enough hot water for more than one shower at a time unless you install the largest model. That usually involver getting a larger electric service or larger gas pipe to feed all that energy on demand.
- They are expensive to install and repair because they have so many more moving parts.
- But they have been getting better over the years.
So I recommend an indirect with a new boiler
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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You could also put a bunch of pots of water on the range and boil them every time you want hot water. Who needs automatic hot water…
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