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Air in aircon seawater system

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 505/508
Forum Description: 505/508 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=13561
Printed Date: 27 February 2024 at 17:28
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Topic: Air in aircon seawater system
Posted By: FalParsi
Subject: Air in aircon seawater system
Date Posted: 03 August 2022 at 19:43
Good evening from wonderful Greece…

I always close the seawater intake valve when I go sailing so as not to introduce air into the aircon seawater system. Today I forgot to do so, and now I am getting the HPF fault on all 4 aircon units. I know everything is in working order, and I believe the HPF fault is because there is air in the system. What is the best way to bleed the seawater cooling system?

Thanks,
Lawrence


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2016 Hanse 505 #120



Replies:
Posted By: FalParsi
Date Posted: 03 August 2022 at 20:08
I should have mentioned that I am anchored in a bay so I don’t have access to shore water to push water through the pump.

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2016 Hanse 505 #120


Posted By: 32mike
Date Posted: 03 August 2022 at 22:08
I had an issue once where the sea water strainer was dry, probably due to the same cause that you suspect. I closed the sea cock and then opened the top as if to clean the filter. It was completely dry. I cracked open the sea cock to fill it and closed it again. Then refit the filter and glass top and opened the sea cock. Then turned the Ac’s on. The pump sucked the water through and everything worked.

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Mike
S/V Dulces Sueños
458 #087
Tampa, FL


Posted By: kipwrite
Date Posted: 04 August 2022 at 01:01
I get an HPP fault most every time I fail to close the Aircon intake seacocks and go for a sail with any degree of heel. 

The easiest way to clear the fault:

1- open AC intake seacocks
2- remove the clear plastic seawater hose from the AC unit (the top hose) - I usually do this at the unit in the salon
3- have a bucket handy
4- have a helper turn on the AC's
5- when you have a good flow of water into the bucket, quickly reattach hose, turn off AC's, tighten hose clamps, and then tidy up. 

On my boat, getting the air out of the AC unit in the salon seems to clear all units.

I think there's a bleed screw on the high pressure pump but I find disconnecting the top Aircon hose in the salon as described works quicker and more reliably. 




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Kipwrite


Posted By: SVZara
Date Posted: 04 August 2022 at 02:14
I must be lucky.  I have NEVER closed my A/C seawater intake.  The system stays primed and ready and runs without issue even after sailing 100s of miles while offshore.  I am surprised this an issue for you guys.

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Marc
S/V Zara
2016 Hanse 505, Hull #129


Posted By: FalParsi
Date Posted: 04 August 2022 at 10:31
Kipwrite, that did the trick. Thank you!
Time to install a burp valve in that location so next time will be less messy.


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2016 Hanse 505 #120


Posted By: Gale Force
Date Posted: 04 August 2022 at 14:18
If You forget to close the seasick the easiest way to solve the problem is to open the bleed screw a few turns until seawater starts to appear then close and switch on pump.A two minute job if you have the correct spammer at hand.
Duncan


Posted By: Arcadia
Date Posted: 05 August 2022 at 06:38
Bleeding air at the pump is the best way since that is where the water is being pushed from. I replaced the small nylon NPS stopper with a same size barb fitting. I then added a 2 foot length of 3/8 clear tubing with a small shut off valve at the end. This makes it a lot simpler to bleed. I fish out the tube, raise it above the waterline and open the valve. The air is quickly forced out by the incoming sea water, but the water will not come up past the height of the hose. I then close the valve and drop the tube back down. This is all done without turning on the pump or messing with the thru hull or strainer. 30 seconds, no tools ! 

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Leon / ARCADIA
2018 Hanse 588
Sag Harbor, NY


Posted By: FalParsi
Date Posted: 05 August 2022 at 06:53
Perfect Leon, thanks!

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2016 Hanse 505 #120


Posted By: Gale Force
Date Posted: 05 August 2022 at 07:26
I will be installing that one next time I am in GF in a few days time.

Duncan



Posted By: kipwrite
Date Posted: 05 August 2022 at 13:37
Thanks! That's a worthwhile improvement. On the list.  

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Kipwrite


Posted By: SimonGH
Date Posted: 10 August 2022 at 14:55
Originally posted by SVZara SVZara wrote:

I must be lucky.  I have NEVER closed my A/C seawater intake.  The system stays primed and ready and runs without issue even after sailing 100s of miles while offshore.  I am surprised this an issue for you guys.


I think it depends on where the intake is on your particular boat.  My prior boat didn't have this issue because i put the intake on the centerline and near the engine, so it would be underwater in almost all conditions.  Another big contributor was the fact that the outlets of the AC cooling water on that boat were above the waterline, so it naturally self "primed".

My 415 has the intake far enough off the centerline so when you heel over about 10 degrees the water drains out.  I think more importantly, the outlets of the cooling water on this boat are below the waterline, so there is "backpressure" that prevents self priming.  The air gets trapped in the pump until you vent it somehow.

I love the idea of a tube and valve.  very clever.

I will say that I'll deal with this hassle over having the cooling water vent above the waterline.  That resulted in slime on the hull and that constant noise of flowing water...



Posted By: SimonGH
Date Posted: 10 August 2022 at 15:00
Originally posted by Arcadia Arcadia wrote:

Bleeding air at the pump is the best way since that is where the water is being pushed from. I replaced the small nylon NPS stopper with a same size barb fitting. I then added a 2 foot length of 3/8 clear tubing with a small shut off valve at the end. This makes it a lot simpler to bleed. I fish out the tube, raise it above the waterline and open the valve. The air is quickly forced out by the incoming sea water, but the water will not come up past the height of the hose. I then close the valve and drop the tube back down. This is all done without turning on the pump or messing with the thru hull or strainer. 30 seconds, no tools ! 



One little comment - you've now made this little tube part of "below the waterline" plumbing.  If it fails for some reason and you're not there, it will eventually cause a real issue if your bilge pump dies or can't keep up with the flow.

I love this idea, my only modification would be to put the shutoff valve on the pump side, then a barb with the hose.  Raise the hose up and open the valve near the pump.  Same result, but you're no longer relying on that clear tube to stop your boat from sinking...


Posted By: Arcadia
Date Posted: 11 August 2022 at 13:07
Yes Simon that would be better, but unless we close all 20 of our seacocks, then we will have plenty of plastic hose below the waterline all over the boat! And, if closing all seacocks is something you choose to do, then closing the Aircon seacock will suffice to protect the bleeder hose. Besides, it may be tricky to mount a valve directly on the pump body. Let me know if you manage it. Thanks.

-------------
Leon / ARCADIA
2018 Hanse 588
Sag Harbor, NY


Posted By: SimonGH
Date Posted: 11 August 2022 at 15:16
Originally posted by Arcadia Arcadia wrote:

Yes Simon that would be better, but unless we close all 20 of our seacocks, then we will have plenty of plastic hose below the waterline all over the boat! And, if closing all seacocks is something you choose to do, then closing the Aircon seacock will suffice to protect the bleeder hose. Besides, it may be tricky to mount a valve directly on the pump body. Let me know if you manage it. Thanks.


Yes, I always smirk at the guidance that says "close all seacocks when you leave the boat".  I'd be there for ages...

What size thread was the NPS to barb fitting?  My pump is some italian thing, so i'm not sure what size the plug threads are - they look metric to me.

ABYC has standards for below the waterline hose, as well as things like double hose clamps etc.  Hopefully the stuff keeping water out of the boat meets those requirements.  I've been generally comfortable with the build quality of my 415 and everything I can see seems to be done properly (more so than my 2019 Beneteau!)

This isn't cheap, but adheres to the below waterline standards (although the pic only has one clamp per connection, which i would double):
https://www.jetthruster.com/webshop/Air-Release-kit-p208898518" rel="nofollow - https://www.jetthruster.com/webshop/Air-Release-kit-p208898518

They sell it to vent air from the jet thruster pump, but no reason it couldn't be adapted for the AC pump.  Interesting to note that they want you to vent it overboard...



Posted By: SVZara
Date Posted: 12 August 2022 at 16:25
Originally posted by SimonGH SimonGH wrote:

Originally posted by SVZara SVZara wrote:

I must be lucky.  I have NEVER closed my A/C seawater intake.  The system stays primed and ready and runs without issue even after sailing 100s of miles while offshore.  I am surprised this an issue for you guys.


I think it depends on where the intake is on your particular boat.  My prior boat didn't have this issue because i put the intake on the centerline and near the engine, so it would be underwater in almost all conditions.  Another big contributor was the fact that the outlets of the AC cooling water on that boat were above the waterline, so it naturally self "primed".

My 415 has the intake far enough off the centerline so when you heel over about 10 degrees the water drains out.  I think more importantly, the outlets of the cooling water on this boat are below the waterline, so there is "backpressure" that prevents self priming.  The air gets trapped in the pump until you vent it somehow.

I love the idea of a tube and valve.  very clever.

I will say that I'll deal with this hassle over having the cooling water vent above the waterline.  That resulted in slime on the hull and that constant noise of flowing water...


Yes, my thruhull is dead center in front of the engine.  I thought all 505 and 508 had the AC raw water input in the same location.  Interesting.


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Marc
S/V Zara
2016 Hanse 505, Hull #129


Posted By: SVZara
Date Posted: 17 August 2022 at 18:48
While we are on this topic.  Where can I get new screen for the raw water strainer for the A/C unit?

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Marc
S/V Zara
2016 Hanse 505, Hull #129


Posted By: Johny
Date Posted: 18 August 2022 at 09:35
https://www.asap-supplies.com/products/maestrini-clear-lid-for-remote-water-strainers-3-4-1-401201%20" rel="nofollow - https://www.asap-supplies.com/products/maestrini-clear-lid-for-remote-water-strainers-3-4-1-401201

ASAP has all the spares for the A/C strainer


Posted By: kipwrite
Date Posted: 20 November 2022 at 21:33
The fitting on the AC pump is 1/4" NPT. 

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Kipwrite



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