City water feed: plumb "after" on-demand pump, or pressurize holding tank(seems bad)?

[freeandeasywanderer]

Questions about water system:

#1) I have seen various schematics/diagrams (both are included in this thread, one is the same as i see in this linked thread ), one that shows the city water hook up placed after the on-demand pump, and one that looks like its pressurizing the holding tank (which seems like a bad idea?). Which style do you use? I want my city hookup to enter the water system after the pump personally, but does a Sureflow need a "back flow prevention valve" or does the pump handle this alone?

#2) does it matter if the on demand H20 heater is first, last or in between? These diagrams also conflict on that, one shows it last in the circuit, one shows it T-ing off first.

#3) What is the "anti-freeze access point"? Do you use this in your bus?

[TheHubbardBus]

City water is pressurized, so you don't need (or want) it running through the pump. So it should Tee-in after your pump, with a one-way check valve between it and the pump outlet to prevent water from flowing backwards through the pump. Often pumps come with their own one-way check valve at the outlet, but IMO it's a good idea to add your own even if it does.

The city water line will also incorporate a one-way check valve, preventing the water pump from forcing water up out of your inlet.

I think it's also a good idea to put a pressure regulator after the city water inlet, in case the source pressure is too high, and to provide for consistent performance / behavior.

The anti-freeze access point is to add (food-grade) antifreeze to your system for winterizing (prevents lines & components from freezing when not in use).

Your water heater needs to be downstream of your sources (pump & city water).

[turf]

neither pic is right, but the second one is more right than the first.

city water is after the pump and a valve of some kind. the valve could be an automatic check valve/backflow, or a cheap butterfly valve.

the water holding tank can not be pressurized. it has a vent and a gravity fill, usually. pressurizing by hooking the tank up to city water would blow a constant stream of water out the tank vent.

water heater can be anywhere. small units are typically under a sink in your house, but used to supply your entire rv.

combine the city fill after the pump and a drain before the pump, and you can suck antifreeze into your system for wintertime storage. you can't pour antifreeze in the tank, because you never get all the water out of the tank. you'll taste antifreeze for years if you put it in the waterholding tank. (ask me how i know). but its an easy way to protect your pump, faucets, toilet, from cracking when they freeze in storage.

otherwise you need to use air to blow out the system for winter.

[freeandeasywanderer]

Originally Posted by TheHubbardBus

City water is pressurized, so you don't need (or want) it running through the pump. So it should Tee-in after your pump,
with a one-way check valve between it and the pump outlet to prevent water from flowing backwards through the pump. Often pumps come with their own one-way check valve at the outlet, but IMO it's a good idea to add your own even if it does.

Got it yeah thats kinda what i had in mind on all topics, tyvm!

[freeandeasywanderer]

Originally Posted by turf

neither pic is right, but the second one is more right than the first.

city water is after the pump and a valve of some kind. the valve could be an automatic check valve/backflow, or a cheap butterfly valve.

the water holding tank can not be pressurized. it has a vent and a gravity fill, usually. pressurizing by hooking the tank up to city water would blow a constant stream of water out the tank vent.

combine the city fill after the pump and a drain before the pump, and you can suck antifreeze into your system for wintertime storage. you can't pour antifreeze in the tank, because you never get all the water out of the tank. you'll taste antifreeze for years if you put it in the waterholding tank. (ask me how i know). but its an easy way to protect your pump, faucets, toilet, from cracking when they freeze in storage.

otherwise you need to use air to blow out the system for winter.

Lots of good info here! TYVM