How's this for better tankless water heater use

I would look for a diesel fired heater- most will give hydronic heat as well.

We spent some time Down Under in Australia in 2000 !

We rented a Sprinter Based Camper Van that had an On Demand Propane fuelled Water Heater that worked very well,for Washing up and Showering! There was no shortage of Clean Hot Water !

I never could find out the manufacturer of that heater!

15A 120VAC is 1800 watts, which is equivalent to 6141 BTUs/hr. This means your heater can theoretically heat 6141 pounds of water 1°F each hour, or about 30 gallons by 25°F. To get a 25° rise you thus need to have a flow of about 1/2 GPM. Their claims seem rather optimistic to me. (It is reasonable to expect a tankless electric water heater to be very nearly 100% efficient at converting electrical energy into water heating.)

If you're insistent on heating the fresh water tank, I still recommend using your existing water heater and pump system rather than buying another heater/circulator unit; all it requires is a bit of plumbing to route the hot water back to the tank. It should be little more than a valve and a bit of tubing and a couple of tees, much of which you'd need to install the block heater anyhow.

Thanks for all the replies. First the water heater is new and is only 15 amps and according to the specs it can only be expected to raise about 20-25 deg. The 20-30A heaters have a much higher temperature rise capability. The heater I was thinking about is like

http://www.amazon.com/Kats-13150-Aluminum-Circulating-Heater/dp/B000BQUUR6/ref=sr_1_2?ie=UTF8&qid=1431292938&sr=8-2&keywords=engine+block+water+heater

I believe the point about the heat rise to the cabin may be the best argument against this. I too wonder about the potability safety but figure something could be found.

I have no room for a bigger propane heater and the propane capacity is depressingly small. Any other ideas?

If the water heater can't be made serviceable and you wish to jury-rig a solution rather than replace the heater, I'd suggest to use one of the portable "camp hot water heater's" and establish a loop into your hot water piping.

There was a thread on the Forum not too long ago where someone did this and provided enough hot water for a dozen people using the shower facilities.

IS this a 'Chronomite Water Heater'?

Probably clogged up with minerals/deposits

Very small unit........
SR-30 uses 120V 30A needs .4 gpm flow to activate 25*F temp increase at 1 gpm

Hardly good enough to warm water let alone heat it

We had block heaters in all the fire engines and ladder trucks to maintain the engines warm while in station, from what I remember they fit in one of the engine freeze plug holes and connect to 120V A/C, even the Battalion Chiefs vehicles where plugged in with engine block heaters.

I believe that this tank-less heater that sprintstream has is not operating correct the water should be a lot hotter, they have used small tank-less heaters in Europe for some time and they do warm the water enough to be able to take a comfortable shower, although not to hot for my wife but hot for me.

Heating the water tank will only waste energy, and if the tank is in the passenger cabin, it will be very uncomfortable in the hot weather with a hot cabin, turn the A/C on full bore and watch the electric meter spin.

Check the unit out first to see that it is working as it is supposed to.

navegator

2005 seems awfully early for a tankless water heating unit. Do you at least have a 50 amp service?

What you're proposing might help, but it's very far from an ideal solution and I wouldn't recommend it. A block heater (at least one made with appropriate materials) won't cause water purity or safety problems. Since they're made for use in engine blocks, though, block heaters generally wouldn't be made with food-grade materials, and certainly wouldn't be certified for use on potable water systems. That isn't saying they would contaminate the water, just that they aren't guaranteed by the maker as not doing so.

There are bigger issues in terms of efficiency and effectiveness. The fresh water tank is usually not insulated, so there would be a good bit of heat loss from it (and heat gain in the interior of your RV if it's within the envelope of the living area). It also holds a comparatively large amount of water, so it would take a long time and a lot of energy to warm up the tank appreciably. Any cold water that you used as such also represents wasted energy consumption in needlessly heating the water.

I suspect at least some block heaters, and probably all, have a thermostat to shut them down at some temperature. It's entirely possible that this may be lower than normal room temperature since they're generally employed during very cold winter months only.

With proper plumbing (basically a valve in a new pipe connecting the hot water line to the tank fill line), you could use your existing water heater and water pump to heat up the water in the fresh water tank. It still wouldn't work very well and would waste a lot of energy, of course, but the cost and complexity and any safety concerns in hooking things up would be largely avoided.

I suspect, however, that the most satisfactory solution would be the obvious one—replacing the water heater with a more capable unit, probably a propane-fueled one given the electrical supply limitations of RVs.

Something is wrong with the heater or the brand sucks