Jump to content

webasto filling loop and pump not kicking in


Poppin

Featured Posts

I've got an interesting problem with the filling loop on my Webasto powered heating. It's a sealed system with no filling tank, so pressure is supposed to be at about 1 bar when resting. I just noticed the pressure at 0! I went use the filling loop to re-pressurize and didn't expect what happened. it pressurised to about 0.3 bar, then nothing more and the pump didn't kick in. I went back to my kitchen tap, opened it and the pump engaged fine, though after I closed it the pump continued for a little bit, obviously filling the pipes near where I just pressurised. So basically the standing pressure in the pipes is enough to charge the heating circuit a bit, but the pump isn't kicking in from the drop in pressure at the back of the boat. Does this mean that the pressure switch on the pump needs adjusting? I did recently replace a 30PSI shurflo with a 25PSI jabsco, could that be the reason? The pressure of the pump must be enough, as the standing pressure it charges the pipes to is enough to charge the heating circuit, its just the pump not sensing the drop in pressure. 

please help!

Link to comment
Share on other sites

9 minutes ago, Poppin said:

I did recently replace a 30PSI shurflo with a 25PSI jabsco, could that be the reason?

Was there any particular reason why you didn't replace like-with-like ?

 

I tend to find things are much simpler when replacing things to use items already proven to work, it always amazes me how a seemingly innocuous change can have a big effect on a system.

 

Not saying it is the pump, but, its added another variable into the 'mix'.

You could have air in the system, could have dislodged some 'clag' etc, various possibilities.

Link to comment
Share on other sites

Possibly the "blocked hole" fault in the pressure switch, assuming it's integral to the pump.  Most such switches incorporate a plastic bit with a small hole in it on the "wet" side of the switch diaphragm. If it gets partially blocked, the pump becomes very slow to respond to the change in pressure in the water system, and also overshoots, so that water pressure varies between almost zero and far higher than the pump is set for. I usually open out the hole to 3mm or so.

Link to comment
Share on other sites

I've a similar pump - a Jabsco parmax 2,something. Anyway, when I used it to pressurise my system, much the same thing. It doesn't like meeting an immovable head of water. I can just about get it to a little under 1bar and the system works ok. If you want to do a better pressure up, wait till you are at a water point! 

Link to comment
Share on other sites

0.3 bar is about 5 psi, so if the gauge is reading correctly, you need to check the pump pressure, but the water out of your taps is a good guide First, check the pressure relief valve on the heating circuit; is it leaking and causing pressure loss? Disconnect the filling loop and ensure that it is passing water to the circuit, there could be a non return valve on one endwhich could be blocked. There should be a bleed valve on the valve which may need relieving. If operating the prv gives a strong flow, evacuate the heating circuit and remove the gauge to check the orifice is clear.

Edited by Ex Brummie
Link to comment
Share on other sites

Pumps switch off at say 25psi but don’t switch on until the pressure is a fair bit lower.  In my case the flow is very low (so low pressure) as the pump comes back on.  So you need someone to open a tap so the pump starts then open the filling valve before the pump cuts off.  That way it should pressurise your system to pump cut off pressure.  Now a word of caution.  If the pressure is low in your domestic system (say just as the pump starts) and you open the filling loop then if the pressure is higher in your heating circuit and you don’t have an effective non return valve then heating circuit water will flow into your domestic water system, though as the pump pressure rises most of it will flow back into the heating system.  But you don’t want to be drinking antifreeze.

Link to comment
Share on other sites

Yes I think this is to be expected, albeit with perhaps an unusually low cut in pressure. The pump setup isn’t designed to feed a pressurised system, it is designed to exit at a tap at zero pressure (relative to atmospheric). So as said, you need to manipulate a tap to get the pump running to get the pressure up, and watch out for back flow.

Link to comment
Share on other sites

13 hours ago, Ex Brummie said:

Are you sure you don't already have a non return valve. Most proprietary filling loops have one, ........ but if someone has cobbled something ..............

No non return valve, there is an isolation valve on either end of the Flexi hose, as well as a spring back lever valve for controlling flow. Bizarre I know. I've been wanting to fit this NRV for a while, but I've just had it isolated until I found time.

Link to comment
Share on other sites

I'm pretty sure you should have a double check non return valve in the filling loop! Otherwise what Chewbacka sais about ending up with antifreeze in your drinking water could possibly happen. The filling loop can also be uncoupled at one end when not in use.

You have an expansion vessel too?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.