Water tank non return valve .

You ask. I deliver. That banky blokes got nothing on me. I’m wasted as a heating engineer.

 

We all know that!

 

You’ve got a definate talent, mate. Do any Botticelli? Venus rising from ocean? Red-haired birds wi’ big chests, that kind of thing.

 

Some pumps are self priming. These can pump air and create a vacuum.

Many centrifugal pumps fail to work when full of air. So they need non return valves and a way of priming the pipework every time you run out of water and get air in the pipe.

Non return valves dont stop air comimg from below. Then they act as a way of ensuring there will be air in the system below the valve.

Otherwise fit the pump at the same level as the bottom of the tank.

Or a priming piston or diaphragm type pump at that level... its why Devon used a largish diaphragm hand pump in series with an electric pump. The diaphragm pump acts as non return valves.

 

Hi . I was gonna fit the NRV just before the in-line pump that is just below the tap . I can’t put the pump at the tank end as it is underslung and the pump would be outside. Do ya think if I put a NRV on the tank end of the pipe that would work ?

 

Is that the look we all have when we put our busses on the ramps

 

I’d think that would be fine. A lot of oil heating systems use this arrangement. The oil pump is inside the boiler and the non return valve is fitted next to the oil tank, this keeps the whole fuel line full, and therefore the pump. Can’t see why it wouldn’t work in exactly the same way with a water set up.

 

If you run out of water in the tank and get air in the pipe up to the tap, you need to make sure that you can back fill the pipe from the NRV to the tap, so the pump runs in water, and that water naturally reaches the NRV by gravity at the bottom so it doesnt suck air.

It will always be a pain until you either get a pump that self primes or fit the pump low down by the tank or in the tank.

And NRVs require suction (or pressure) which you lose if any air bubbles get in the pump. And they tend to stick shut.

My Devon set up is only saved by the massive hand pump that can suck all the air through the pipework before the electric pump starts working. And there its only lifting the water about a foot.

 

Before fitted a NRV, I solved the problem simply by putting my mouth over the tap and sucking.

 

Ah, the old Yorkshire method . Teach those soft Southerners a thing or two.

 

Any recommendations for a small self priming pump to reduce all this hassle?

 

I use a Shurflo; it’s mounted under the worktop near the tap and sucks from the underslung tank without any problems. https://www.amazon.co.uk/CARAVAN-MA...i 12v&qid=1557597350&s=sports&sr=1-3-fkmrnull

 

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/292063852298

 

Got the water sorted . Liked the sucking it through the tap method. Result

 

Used the sucking through the tap method to prime

 

The old ways are always the best. No need for all this high tech stuff!