Originally Posted by maricard
If I understand properly the system, when you want to use hot water for a shower few minutes after shut down your engine, you turn on the circulation pump, you use the shower and you turn off the circulation pump up to next use. Am I right?
If the engine is cold, you turn on the circulation pump and the hydronic, you wait some minutes (how long do you think?), you use the shower and you turn off everything until next use.
Without reservoir you have to do this sequence each time you want hot water. Isn't it?
Yes, but when using the flat plate only (engine hot but not running), as the radiator water cools you have to adjust the hot/cold mix. I've been able to get two full "submarine type" showers when it's in the 70's outside. I never took the time to shut it down... I was in & out w/i about 10 minutes and it was ready for the next occupant. One thing I've found (especially for the ladies) is to use a water-less shampoo
prior to the shower. Washing hair seems to waste a lot of water. There's no need to rinse out the water less stuff
but even if you do it doesn't take much to do a quick hair rinse if you want to compared to trying to rinse out regular shampoo. I only have a 18 gallon tank so I try to be as conservative as possible.
Sorry I can't say how much longer the engine would have supplied comfortably warm water past 30 or so minutes.
There is no need to turn on the additional circulating pump when using the Hydronic itself as it has its own pump. In fact it will (using the additional pump) waste battery power.
In most cases depending on how cold it is and how fast the unit fires up, hot water at the sink is 3 or 4 minutes away. For some reason my Hydronic will fire up and then shut down, then automatically re-cycle and start. After you hear the unit run at full speed the flat plate sends hot water on its way. Because (like most homes) it takes a while before the hot water reaches the tap, I capture the cold water if need be. That water can be used for washing dishes and what not...why let the water run as waste? It also makes a difference where the shower wand is connected with respect to the flat plate. I have two wands, one at the rear doors and a portable wand that plugs in on the side of the van a foot away from the flat plate. FWIW the rear wand takes longer before the hot water reaches it.
The nice thing about the Hydronic is it supplies hot water quickly and when you're done just turn it off until you need it again where as the flat plate requires you to get the engine at running temps or actually keep the engine running while you shower as the engine warms. Most all the units require a tempering valve in the build. Mine was one of the first and didn't have one and the water almost burned me a few times. I now have one.
I'm not sure what you mean by "without a reservoir" but if you mean using water from a constant supply, I think each will work. The espar will supply hot water as long as it is turned on and so will the flat plate only provided the engine is running. The only reason to have the secondary circulation pump is so you can use the engine as an insulated water tank that provides hot water for a limited time with the engine shut down. Many people just run the engine (no pump at all) to supply hot water via the flat plate. The flat plate works similar to a heater core and the vehicles water pump forces water through it.
I do not know anything about the D-5 Hydronic or its operation only that it doubles as a cab heater. My water heater is very loud while it cycles on and off compared to my Airtronic. I'll let those with the D-5 comment on that unit.
Hope this helps.