Plumbing head (ache) xm

[paulburton44]

I think i have finished plumbing in my new xm electric sea loo !
1st problem the xm comes with 2 adapters ! the pump has inlet and outlet of about 1inch then you get these adapters to convert down to 3/4 and up to 1 1/2. but you still need to get some short bits of 1inch pipe and several jubilee clips.
I have fitted vented loops on the inlet pipe and the outlet !! is this right ?
the loo is about 10 inches below the stationary waterline.
My concern is the big warning label that says do not run dry !!!!
Will the vented loop on the inlet empty the pipe, hence the pump will run dry untill it has primed itself ?
I take it the pump is self priming ???

 

[snowleopard]

a vent pipe on the inlet will allow the pump to suck air. air will get in through the valve more easily than water will be sucked in so it may never prime.

 

[HeadMistress]

Your concern about the vented loop in the intake causing the toilet to run dry is valid...the dry friction heat from running dry will destroy the intake impeller. An electric toilet requires an electric solenoid valve (electrically operated vented loop) in the head intake instead of a vented loop. Jabsco makes one...part # 37068-0000...I don't know who else in the UK does, but the Jabsco can be used with any toilet. It's wired to the flush button, so that the air valve closes to allow the toilet to prime when the flush button is pushed, opens to break any siphon when the flush button is released. You can see an example of how it should be installed here (drawing at the bottom of page 2): http://www.jabsco.com/prodInfo/overview/37010-0000_ds.pdf It's one of Jabsco's electric toilets, but the same instructions apply to all electric toilets.

I'd also suggest that you replace the 1" discharge fitting on the toilet with a 1.5" fitting...they're pretty standard, available in both straight and 90, so any should fit your XM...thus eliminating the need for any adapter fittings.