Fresh water system pressure tank

[Sea Escape]

Hello everyone, I am new here, just bought an old Bavaria 390 and we started refitting some systems, including the fresh water system.
My first thought was to install a fresh water pump with a pressure tank but I suddenly realised that I don't know what size of tank would be ideal.

We're going to have 2 faucets and 1 shower in a first time (probably adding 1 more faucet and a deck wash later) and the system I was looking at is a 10 LPM pump with a 1L pressure tank. What do you think?

Cheers,
C.

[Yngmar]

1L should be fine. Ours seem to fail a lot (3 in 5 years), but that's with liveaboard, so lots of use. The membrane types seem to last less well than the plain air ones, but the air ones you must occasionally drain (about every 3-4 weeks, so make sure it's somewhere accessible).

This type lasted the longest so far: https://www.comet-pumpen.de/en/products-rv/pumps/accessories/pressure-tank.html

My other advice is to mount the pump low, so it doesn't have to struggle sucking water up from a tank if the pipe got empty. Nearer the tank is better for the same reason.

The Whale quick-connect fittings and semi-flex pipes are superb and highly recommended.

[tiger79]

A lot depends on your choice of freshwater pump.  My boat was factory-fitted with a Whale Watermaster pump, which is a 4-chamber type, designed to give a smooth flow.  There's no additional pressure tank fitted, and the system works well.  So, you might not need a pressure tank, depending on which pump you choose.

[Jeffatoms]

Please remember that in most cases your fresh water system is separated into two side; hot and cold.  What many people fail to recognize is the hot water side charges up to the full pressure of the fresh water pump and remains static until the hot water/calorie energizes when then causes pressure to build on the hot water side only due to the hot water check valve.  Please consider adding a second similarly sized accumulator on the hot water side between the check valve and the heater/calorie to regulate pressure in the hot-only system.