on-demand hot water heaters

[N7SJN]

Does anyone have any first hand knowledge of one of these heaters. I have some concerns about the temp of the incoming water. I have seen them used in low volume applications, but not for a long shower. We are in areas where the incoming water temp can be 40 deg F or less. Our six gallon heater struggles to keep up with even a "navy" shower.

[reddwar]

I here some folks say when water temp varies with water pressure. Why don't they just turn on the pump & water pressure should not vary, if they have city water there tank should be full. I find the out side temp will change my water temp.

In south central Kansas we built a 40X60 barn with 16' lean-to. Have a 30X16 patio with 3 9' garage doors so the light comes in on our 5er. The other half of lean-to has R19 walls R30 over head, with a bath.

Installed an elect. ECO smart tankless hot water heater in our barn as we spend our winter in TX & AZ. The ECO smart says the 11 I installed is good as far north as Oklahoma. It can use up 57amps, ECO smart said needed there 18 for Kansas 75.0 Amps. It works great in the summer in fact we set it at 96 & no cold water I can reach the temp from in the shower. Last winter when we came home for Christmas it was -0 & had to turn it all the way up to 140, the water was not hot but was warm so we could take a shower.

I am sure in an RV it would have to be gas as it would take to much elect. As a old RV'er we wet down, soap down, rinse off. When I turn water off & then turn it back on the water it is old water so just right then it gets cold for to long then hot for a little bit then back to just right. Like I said the heater is so close that I can change the temp from shower. Do not wash my hands in hot water as I am done by the time it gets hot & yes I can reach the heater from the sink.

[64thunderbolt]

see my post in this section on tankless water heaters

[Jessie_Jane]

Generally temp rise will affect flow of warm water, as will incoming flow rate to the water heater. Increase of the cold to temper the water and you slow down the flow, essentially shutting down the heater.

[N7SJN]

Thank you for all the comments. I was concerned that the delta T would be the prime factor not the water pressure. To those who have them and are satisfied, thank you for your contribution.

[mvpmich]

N7SJN wrote:
Does anyone have any first hand knowledge of one of these heaters. I have some concerns about the temp of the incoming water. I have seen them used in low volume applications, but not for a long shower. We are in areas where the incoming water temp can be 40 deg F or less. Our six gallon heater struggles to keep up with even a "navy" shower.

Just had the factory installed unit removed and a standard 10 gallon, gas/electric unit installed in its place after the manufacturer had replaced the original on-demand with a newer model. The basic problem is that water pressure effects temp. No two campgrounds have the same pressure. Therefore the temperature us always changing requiring constant adjustments.

The coach water pump also produced less than adequate and constant pressure leading to fluctuating temperatures. Adding to the problem, is that it takes awhile for the initial water flow to heat up and the heater works best if a constant flow of water is maintained. This unfortunately is a direct contradiction to why we upgraded from a C to an A for larger holding tank capacities only to fill the larger tank as fast as the smaller one in the C.

Lastly, the DW was not a happy camper with the on-demand unit. Need I say more?

[Chris_Bryant]

The only one I have worked with is the PrecisionTemp RV500- rated for an 85 degree per gallon per minute temp rise- should be plenty in all but the coldest weather. It also uses a modulating flame along with a flow rate sensor and thermostat to keep the water at a set temp. Every customer who has used them will not live without them, but they all like long hot showers, and do not boondock.
Not cheap though...

[Dick_B]

This has been discussed. Try searching this forum for `water heater' then search the results for `on demand'. I think the consensus is that such heaters are not ready for prime-time RVing.

[dougrainer]

Jayco and Tiffin have offered On demand as an option for about 3 years. From what I have seen and tried to fix, I would NEVER have one in an RV. They are a constant source of complaints by my customers. Yes, incoming water temp does affect the output temp. The amount of volume running thru the heater also affects the output temp. A CONSTANT complaint is uneven hot water output from scalding to then too cold in a manner of seconds. We do not option them anymore unless a customer requests one on a Order for a new RV. WE also advise them of the problems, and then let them make the decision. Doug