Shurflo Trail King short cycling

[cmcardle75]

I'm having some issues with my new water installation. It uses a 30psi 10.6lpm Shurflo Trail King 10. All pipework is new. It is run in a mixture of 15mm domestic pipework on the inlet side and 1/2" bore reinforced food grade hose on the output. Outletwise there is a kitchen tap, basin tap, thermostatic shower and toilet. Tank is actually located at same height as pump.

Unfortunately, it is short cycling very badly (i.e. about once per second). Only the basin tap (which is a domestic type) has enough flow to stop the cycling. The shower and kitchen tap (both caravan types) short cycle badly. The impression at the outlets are that both the pressure and flow are weak, much worse than a caravan with a £10 submersible pump. There is no entrained air (at least after the hot tank is full).

Inlet filter is clear. No hose kinks. Tank is vented. A Fiamma A20 accumulator pre-set to 2 bar makes no difference/makes the cycling actually slightly worse. This is a brand new installation and has never worked properly. There's a few elbows in the system, but I can't imagine they'd restrict flow this amount.

I'm stumped. It feels like a restriction in the pipework after the pump, but there is nothing I can find and 1/2" reinforced hose is pretty hard to block. Could it actually be the pump itself? Any ideas?

 

[mike mcglynn]

I seem to recall that there is trim screw on those pumps , have you looked at the diagrams for your model ?

 

[cmcardle75]

Yes, I did try fiddling with it. Although I understand all it does is modify the "off" pressure. It had little effect.

 

[rb62]

Have you tried the system without the accumulator?

 

[Robert Clark]

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Make sure you have got all the air out of all the pipes, don't forget the loo flush.
I recently fitted the same pump to my Hymer to replace the submersible pump.

I had a different problem I was getting a lot of vibration on the shower mixer, I realised I hadn't run any water through my shower tap in the garage after opening the tap and running some water through it was all fine. I didn't need an accumulator on mine it runs fine without pulsing.

Although the flow rate on the submersible was 19Lt/min and the Trail King is 10.6Lt/min the pressure and flow at all the taps is much better with the Trail King.

I also found adjusting the pump pressure switch didn't really make any difference.

 

[cmcardle75]

Have you tried the system without the accumulator?

Yes, it improves very slightly without the accumulator, which is extremely odd in itself.

 

[rb62]

A few suggestions here

Pulsating Water Pump

Our water pump has started to pulse when the water filter or shower are used. The pulsating does not occur when the kitchen and bathroom sink taps are used. We have a Shurflo Pump which was fitted late last summer, and has been fine till just recently. The cold water system is coupled to a...

www.motorhomefun.co.uk

 

[cmcardle75]

Well I've ordered a much larger accumulator. 8 litres rather than the 1 litre Fiamma. We'll see if it short cycles just trying to fill the accummulator!