A/C-Heating Dockside Flush Install

[uppy22]

I have a '99 270DA that has the optional a/c and heat. I want to install a dock-side flush quick-connection in the bilge in-line between the seacock and the strainer so that I can flush the system dockside instead of only when I'm on the trailer. This was done by the previous owner on my genset. Has anyone done this? Looking for advice on the best fittings to use, what size the existing hose is (so I know what size fittings I need), and any tips on the project. Seems like this could be accomplished with one t-fitting, two ball-valves, and a section of hose. Splice the t-fitting into the line, install one ball-valve between raw water intake and the fitting, one ball-valve between the new hose/quick connect and the fitting, then send the third prong of the fitting to the A/C unit. Then just open the ball-valve you want the source of water to be and close the other. Anyone see a flaw in that?

 

[dpmulvey]

I don't know the setup so I'll give you mine FWIW! The 330 pee tube exits under the front berth. There is a ball valve already there for some reason. If you have a similar setup, all that is necessary is to fit a "T" before the ball valve that has a garden hose fitting on it. Attach a hose. Close the valve. Turn on the hose. Back flush the system to include the strainer out the seacock.

YMMV.

 

[JimFromMD]

I was going to suggest backflushing system by pushing water back through the throug hull fitting and out the bottom. There are several approaches depending on how/if you can reach the AC through hull where the cooling water comes out.

One is to force water back through with a garden hose. You can use a jet nozzle attachment with a rag/towel wrapped around it. There is also a plunger device with a garden hose attachment that you hold tight against the side. Use your favorite search engine with "Moeller Flushrite Boat Motor"

Another option would be to close the seacock and use the seaflush device from inside the bilge. seaflush.com

Lastly, in one of the winterization threads, someone here suggested using a test titan plug in your sea strainer. I found them at home depot, but didnt have a chance to determine which size and get one before the end of the season. Search for "test titan mechanical test plug" on home depot's site. Looks like it would work perfectly if you drill out the center of the threaded end. Inexpensive solution too.

 

[uppy22]

I don't know the setup so I'll give you mine FWIW! The 330 pee tube exits under the front berth. There is a ball valve already there for some reason. If you have a similar setup, all that is necessary is to fit a "T" before the ball valve that has a garden hose fitting on it. Attach a hose. Close the valve. Turn on the hose. Back flush the system to include the strainer out the seacock.

YMMV.

Thanks David. Sounds like my setup is somewhat different. My intake originates in the bilge, then runs behind the mid-berth to the heat/A/C unit that's under my dinette. So the tube is easy to get to in the bilge area.

It sounds like your setup only flushes the intake, but not the actual heater/AC unit, is that correct? Wouldn’t you want to flush the actual unit to get the raw water out of there? I run in Puget Sound so want to clean the salt water out.

 

[uppy22]

I was going to suggest backflushing system by pushing water back through the throug hull fitting and out the bottom. There are several approaches depending on how/if you can reach the AC through hull where the cooling water comes out.

One is to force water back through with a garden hose. You can use a jet nozzle attachment with a rag/towel wrapped around it. There is also a plunger device with a garden hose attachment that you hold tight against the side. Use your favorite search engine with "Moeller Flushrite Boat Motor"

Another option would be to close the seacock and use the seaflush device from inside the bilge. seaflush.com

Lastly, in one of the winterization threads, someone here suggested using a test titan plug in your sea strainer. I found them at home depot, but didnt have a chance to determine which size and get one before the end of the season. Search for "test titan mechanical test plug" on home depot's site. Looks like it would work perfectly if you drill out the center of the threaded end. Inexpensive solution too.

SeaFlush seems like a winner to me. Never seen that before but looks like a winner!

 

[Lazy Daze]

I would second Jim's comment about keeping things simple and just backflush it using the thru-hull on the side. Obviously do what's best for you, but I like keeping things simple whenever possible.

Just out of curiosity - along the lines of what you're asking, have you converted the engine to FWC?

 

[uppy22]

I would second Jim's comment about keeping things simple and just backflush it using the thru-hull on the side. Obviously do what's best for you, but I like keeping things simple whenever possible.

Just out of curiosity - along the lines of what you're asking, have you converted the engine to FWC?

I didn’t convert the engine to FWC, but that was done by the original owner. My boat sits on the dock all summer, so it’s a must for my setup. Is there an easy way to back flush the engine though? Would be nice to run some fresh water through there every so often over summer when I’m between trailer pulls.

 

[uppy22]

If I choose to back flush the system by using the plunger device (have one already), is that literally plug and play? Just make sure the seacock in the bilge is open, then put the plunger on the through-hull water exhaust hole and turn it on? That won't damage the pump or anything else to push water the opposite direction? I can easily reach the through-hull exhaust hole from the dock, so this would be simple.

 

[Lazy Daze]

Nope, won't hurt anything (AC system). I use a handheld pump (an old gear oil pump) to do this.

Engine... why flush it? You mentioned it's already fresh water cooled? Is it a full system or a half system?

EDIT: Got knocked off. Well, the cheapest way to flush the heat exchanger and exhaust (assuming half system) is reach over and attach a muff to the outdrive.

 

[dpmulvey]

Thanks David. Sounds like my setup is somewhat different. My intake originates in the bilge, then runs behind the mid-berth to the heat/A/C unit that's under my dinette. So the tube is easy to get to in the bilge area.

It sounds like your setup only flushes the intake, but not the actual heater/AC unit, is that correct? Wouldn’t you want to flush the actual unit to get the raw water out of there? I run in Puget Sound so want to clean the salt water out.

My unit too originates in the bilge and in true engine room design fashion, impossible to reach. Goes forward just port of centerline to the unit under the forward berth and exits starboard under the forward berth. A backflush merely reverses the flow through the entire system and out the seacock. It's the same way I primed my Regal when it came off the rack in dry storage.

 

[JimFromMD]

SeaFlush seems like a winner to me. Never seen that before but looks like a winner!

The plunger device works well for me, but my boat is on a lift. Having not tried it in the water, I dont konw if you could backflush against the sea water pressure under the hull. I dont think it would be a problem, but I dont have any experience trying it. Others may be able to answer that for you.

If I didnt already have a sea-flush, I would give the titan test plug a try first. Seems like a good experiment for under $5. I may try it just for grins next season anyway.

If you do go the sea-flush route... you may need to find a sheet of rubber or something that can serve as a gasket between the funnel and the edges of the strainer. They show how to use a paper towel in their "how to" videos, but I didnt have success with that the last time I tried. I didnt get a chance to dig up something better this season, so for winterization I drained the strainer and then backflusheduntil solid pink was shooting out under the boat.

 

[uppy22]

Nope, won't hurt anything (AC system). I use a handheld pump (an old gear oil pump) to do this.

Engine... why flush it? You mentioned it's already fresh water cooled? Is it a full system or a half system?

EDIT: Got knocked off. Well, the cheapest way to flush the heat exchanger and exhaust (assuming half system) is reach over and attach a muff to the outdrive.

I will admit that I’m not real mechanically inclined. I believe that I have a half system since it’s aftermarket. Anytime I have it on the trailer I use the muffs to flush it out.


Regarding the back flush of the heat/AC system, if I use the plunger and my dock hose (has an unheard of amount of pressure) will that be enough pressure to push through the system?



Thanks everyone for all the help. Love the quick and knowledgeable responses on here.

 

[bbwhitejr]

I went to HD, bought a 1 1/2" PVC plug with a 3/4" threaded hole in the top of it, and screwed a 3/4" threaded nipple in it. I have the polycarbonate threaded caps that go on my strainers. Remove the cap, screw in the PVC fitting, hook the hose up to the nipple, and turn on the water. Less than $3. Works like a champ....

Bennett

 

[JimFromMD]

Even bettter!

 

[themikehyde]

Here was my solution. I believe I bought them at yachtsofstuff.com

 

[Lazy Daze]

Regarding the back flush of the heat/AC system, if I use the plunger and my dock hose (has an unheard of amount of pressure) will that be enough pressure to push through the system?

I've never had a need to try it in the water, but I think it should work. It's gotta at least flush out the compressor, which is the main thing you want to do. How well it flushes out the hoses and strainer in the bilge - I don't know. But those are less important since they'll fill right back up with sea water, anyways. If you can have someone watch the strainer, you'll know for sure.

An interesting test would be to stick one end of a hose (snugly) into the hull-side thru-hull. Attach the other end to a bucket or jug of water and hold that up on deck. See if gravity alone will flush it out.