The waste heat is coming from your comments? *grin*.
On the electric setting the tank units are nearly 100% efficient. Propane I have no idea.
mchero wrote: This one cracks me up;
"RVs do not have enough power available to operate a practical electric tankless water heater"
OP was referring to a PROPANE tankless hot water heater. People need to think B4 they type.
Does anybody know the true efficency rating on a standard RV hot water heater? From all the heat comming out of the exhaust port I bet it is not very high.
I remembered a few months ago, people were saying that Atwood was going to come out with a worthy product for the tankless on-demand water heater RV market. Just checked their Website and PPL, and even it appears that the models are not out yet, the 45K BTU model is $860, the 50K BTU model is $900. A tad expensive, but for a unit that takes less space than a conventional six gallon WH, it might be something to consider. Were I keeping my TT for good, it would be a no-brainer to buy the Atwood.
The Atwood also uses a different mechanism to adjust water than the Girard. It doesn't care about the amount of water flow, you just mix it with cold water like you normally do with a standard tank type. Plus, it will keep water over 112 degrees even in 40 degree weather (which is important, and a main complaint about other tankless brands.)
Personally, I want to see more people buy and use the Atwood design, but from what has been said, it definitely is the best tankless design for RVs going so far.
Lantley wrote: My tankless heater waste water in my stick home because you have to let it run a bit to clear pipes of existing water until you get hot water. In a stick house this is not an issue. On full hook ups this is not an issue. However when running off fresh tank or when no sewer is available water conservation is an issue. The water passed until hot water is available is and issue.
This passed water is essential a waste it drains fresh tank and fill gray tank unnecessarily...
And the same doesn't happen with a tank type water heater in an RV? I seriously doubt that any RV has the recirculating loop some stick & bricks with tank type water heaters do to keep the water in the pipes hot. You will have to run out the cold standing water in the pipes to get hot water with either kind of water heater. Thanks for clarifying what you said but it doesn't really apply to RVs.
Well, you would be wrong about the recirculation pump. I know of two folks who have retrofitted such a device.
I chose the "poor man's" recycling system and catch the water in a 750 ml container (that's 3 cups to the metrically challenged). That water is used to assist the next "flush" of the throne.
"RVs do not have enough power available to operate a practical electric tankless water heater"
OP was referring to a PROPANE tankless hot water heater. People need to think B4 they type...
YOU crack me up. The topic of this thread is TANKLESS WATER HEATERS. The OP posted, "Anyone run them in there R.V? .. how well do they work and are they worth the $500.00 price tag? .. the wife likes her 400* baths and the water heater we currently have just cant keep up with her .. lol .." Nowhere was propane even mentioned!
The quote that you inappropriately took unattributed and out of context was a response to the OPs comment that he could get a tankless water heater for only $500. A price that low had suggested he was looking at a low yield electric unit that would not have met his (or, rather, his wife's) needs. 50A @ 240W simply does not have enough energy to power a tankless water heater, even though it's operating for a short period of time.
Well, you would be wrong about the recirculation pump. I know of two folks who have retrofitted such a device.
I chose the "poor man's" recycling system and catch the water in a 750 ml container (that's 3 cups to the metrically challenged). That water is used to assist the next "flush" of the throne.
Recirculation loops in S&Bs don't always have a recirculating pump; the ones that don't (which is most of them) work by convection. My parents had that kind of system in their house.
I have yet to hear of an RV that had a FACTORY recirculation system installed. Anyone can retrofit almost anything. If using a recirculating pump instead of convection, one could install one even on a tankless water heater as long as the flow rate was high enough to cause the water heater to fire. If one had to conserve water, it would be worthwhile to flip the switch on the recirculating pump until the hot water arrived, then switch it off and use the water as normal. Considering most RVs put the water heater close to the shower and sinks, it may not be worth the effort for the amount of water saved.
This is an interesting topic for me because our 6-gallon heater only gives us one--maybe 2--rushed showers. When our whole RV weekend is about rest and relaxation, having to do a mad dash while soaping up and rinsing is the total opposite of that. We always use full hookups and with a family of 7, it would be nice not having to ration hot water.
I noticed on Jayco's website that the 2012 Greyhawks have a tankless water heater option for only $214. That sounds very reasonable to me.
mlts22 wrote: I remembered a few months ago, people were saying that Atwood was going to come out with a worthy product for the tankless on-demand water heater RV market. Just checked their Website and PPL, and even it appears that the models are not out yet, the 45K BTU model is $860, the 50K BTU model is $900. A tad expensive, but for a unit that takes less space than a conventional six gallon WH, it might be something to consider. Were I keeping my TT for good, it would be a no-brainer to buy the Atwood.
The Atwood also uses a different mechanism to adjust water than the Girard. It doesn't care about the amount of water flow, you just mix it with cold water like you normally do with a standard tank type. Plus, it will keep water over 112 degrees even in 40 degree weather (which is important, and a main complaint about other tankless brands.)
Personally, I want to see more people buy and use the Atwood design, but from what has been said, it definitely is the best tankless design for RVs going so far.
Atwood teamed up with Precision Temp to design their new tankless water heaters. Many, if not most, of the components are the same as the ones used that have been used in the Precision Temps for several years with a fairly good track record. From comparing them, it appears the Atwoods crammed the same components into a smaller space, which gives more installation options (the Atwoods will fit where a 6 gl tank type water heater was meant to fit into whereas the Precision Temps require the room a 10 gl tank type water heater needs) which may make servicing a bit tougher. Also, Atwood hasn't been publishing as much info about their water heaters as Precision temp has. I've exchanged several emails with Atwood and it appears their performance is comparable to Precision Temps' and may be a bit better. One thing their literature doesn't tell you is the 50,000 BTU has cold weather capability that the 45,000 BTU model doesn't have. Atwood also seems to have overcome the road splash issues the Precision Temp RV500 has been known to experience (the new RV550 isn't mounted in a sidewall so it shouldn't have problem).
Last I had heard, the Atwoods were delayed due to problems getting certain parts that met their standards but should have been released by now. Apparently, they are still having problems. While the Gerard is a good unit (I have seen it in operation and it puts out plenty of hot water for a scalding hot shower), the Atwoods would be less hassle to use, have more output for simultaneous, multiple points of use and will most likely have a better service network than the Precision Temps. They are also less expensive than the Precision Temps. I'm in no hurry to get one so I can wait. Someone who is in a hurry and has the room could just shell out the extra shekels and get the Precision Temp.
VirtualGarage wrote: ...I noticed on Jayco's website that the 2012 Greyhawks have a tankless water heater option for only $214. That sounds very reasonable to me.
Those are Gerards and I have seen some complaints about them. While user error could be much of the problem, it appears Jayco failed to ensure there would be enough waterflow to allow the water heater to work properly.
The "Precision Temp" tankless is set at 115 F. The water in the tank type may be 180F.
A six gallon tank might give you an 8 minute shower. If it has both electric and propane heating, add 30 seconds?
A ten gallon might give you 40% more than the above, or about 12 minutes. My typical shower time at home is well under both those numbers.
Recovery time on gas for a ten gallon unit may be 30 minutes (delta T of 4.666 per minute) for ground water at say 40 F. On electric 90 minutes (delta T of 1.55) and combined electric and propane about 24 minutes.
I suppose if we went with 115 as an acceptable temperature the recovery time would be around the 12 minute mark running electric and propane together.
I can see why tankless would be an attraction for a large family.
* This post was
edited 05/22/12 04:13pm by pianotuna *
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