Fresh water system 28te

[Pete]

where is the domestic freshwater expansion tank ? my pump runs constantly when using water sounds like it's about to fill exp tank and shut off but never does I assume exp tank needs replacement can't find it.

[Tree]

Check your compression fittings on the pipework first - my guess is it will be those that have come off.

Switch the water on and start by looking in the middle hatch - if you see water leaking into the bilge follow it back to the cause.

Another area to look in to is the pressure relief valve on the hot water tank - if left for a while not under pressure the seals can tend to dry out and fail once under pressure - lots of threads on the forum about it including one I created. Search Calorifier.

[DougSea]

Our 28 didn't have an expansion tank. Just a demand (pressure switch) pump. If you have one it's probably in the area of the pump.

Sounds like you either have a leak as Lee suggests, or the pressure switch has gone bad on the pump. If the pump is running constantly I'd guess it's the switch. A leak bad enough to keep the pump running is usually noticeable and even a broken expansion tank (diaphragm) will fill eventually! Replacement switch modules are available for some pump models.

I should mention that it can also be a feed problem. On our 35 we had a clogged filter on the supply side of the pump and it would starve the pump for water. So the pump would run and run.

[JackK]

Check the supply line to the pump. If it is drawing air it will never satisfy the pressure switch and will continue to run. On my 28, there is an elbow just off of the water tank that I disconnect to use for pumping antifreeze. That fitting wore out and was allowing air into the system which prevented the pressure switch from turning off the pump.

Jack

[Pitou]

where is the domestic freshwater expansion tank ? my pump runs constantly when using water sounds like it's about to fill exp tank and shut off but never does I assume exp tank needs replacement can't find it.

In the absence of a leak and if the pump only cycles / pulses when the fresh water faucet is turned on, that is normal as the pump is needed to make the water flow.

On the 28, they were not fitted with an "accumulator tank" or sometimes referred to as bladder tanks. Jabsco & Shurflo make smaller "accumulator" tanks and they can be fitted after your fresh water pump to help prevent cycling. I have the small Jabsco in my 31 and it does prevent some cycling, but if the water is running for a longer period as when washing dishes or showering the pump still cycles, but not continually. There are larger accumulator tanks made, but with the space constraints on smaller boats they are not practial.

Expansion tanks are for hot water heating systems not domestic water supplies.

[DougSea]

Thanks Kevin, my brain wasn't working when I posted my reply. I knew they were called accumulator tanks but could not for the life of me remember the term! I'm pretty sure the OP was in fact referring to an accumulator tank.

[carolmarie]

On our recent trip we used too much water and didn't realize the tank was near empty so the pump ran continuously sucking air/water.