Badger Navien solution for tight spaces
The domestic water heating industry uses an energy factor, which is almost as useless as the AFUE rating used by the heating industry. Application and installation or operating efficiency (every bit as important as combustion efficiency) is hard to calculate and thus ignored. But with the standard tank type water heater there is little to go wrong; and little to do to improve efficiency. You are stuck with about 35% of the fuel you burn to make hot water going up the chimney instead. The good news is is that conventional water heaters only last about 10 years, so you are liable to get a chance to replace yours very soon!
Tankless Water Heaters
have been around for decades. In fact, I installed my first Bosch tankless back in the 1980’s. Their proper application is to dedicated service for fixed flow fixtures such as a shower and additional occasional use appliances such as a dish washer and wash machine.
If, however, you expect to fill a large tub (over 50 gallons), in a reasonable amount of time, some sort of tank storage would be in order, e.g. indirect water heater or condensing tank/type water heater, properly sized to the load. This caveat is even more critical the farther north you live and the colder the potable water gets as the outdoor temperature drops in winter.
The main advantages of any tankless water heater are; space saving wall-hung feature and the “endless” DHW they provide when properly sized, applied and serviced, And, if they condense, they should cost less to operate than a conventional atmospheric or power-vented tank/type water heater, but “endless” hot water is not free!
Here are reasons I would not use a tankless water heater for radiant heating:
- The heat exchangers are usually made of copper, which wears out with continuous use, not to mention the buildup of scale after a couple of years continuous operation, whereas most condensing boilers are now use all stainless steel heat exchangers.
- Tankless heaters are not warrantied for dedicated or combination space/DHW heating.
- Less expensive tankless water heaters do not have much variance in temperature settings and do not have an outdoor reset function built-in as do all condensing boilers.
- Tankless water heaters require two pumps in order to overcome head loss in the heat exchanger, which results in higher pump cost, higher pump operation cost and often more noise. Though most condensing boiler manufacturers recommend primary/secondary pumping, we find that most systems do not require it.
Finally, there is the service thing. Having worked professionally in both the plumbing and the HVAC fields I have noted that plumbers rarely get proper training in electricity, diagnostics or appliance service. These same plumbers ironically are the only people licensed and presumably “qualified” to install tankless water heaters. It would be a good idea to call your prospective tankless water heater installer before you contract them and ask if they service the brand you have in mind.
High efficiency (condensing) gas-fired appliances are more efficient than their old-school, low-efficiency cousins and will pay for themselves if properly, and regularly, maintained by qualified technicians.
Indirect-fired Water Heaters
If you have a boiler or intend to replace your old boiler with a new high efficiency boiler you will want to consider the unmatched performance of an indirect water heater. An indirect is super-insulated water heater with a coil, like an extra zone, driving water produced by a 98% efficient boiler through the tank. This application allows you to shut down combustion air and chimney saving fuel like nothing else.
An indirect-fired water heater should last 30 years, has no moving parts and is more efficient than any tankless water heater made, without running short of water.
Combination water/space heaters
Bradford White’s Combi II is the most popular combination, water/space, heater available. Though they are pricey and only 80% efficient, they have the distinct advantage of providing space heating and domestic hot water in one neat package, can usually fill the biggest tub, and usually be installed in the same footprint as your existing domestic hot water heater.
We are licensed by the State of Minnesota, MSP, certified by Bradford White and other manufacturers to replace any water heater under warranty. The Bradford White Combi II water/space heating systems takes a special understanding of radiant floor heating that the average plumbing company lacks entirely. Please remember that four-color yellow page ads do not qualify the technician that shows up at your door.
One of the ultimate combination space and domestic hot water heating systems is pictured below. At 96% thermal efficiency, PVC vented, low NOx and SOx, sealed combustion (whisper quiet) and coupled with a sub-system capable of outdoor reset, you have the most efficient and comfortable gas-fired comfort system available anywhere!