Boat Plumbing Questions

On a correctly plumbed hot water circuit, we would expect the average 70litre calorifier to take no more than an hour of engine time to heat. Longer than this and there's some kind of problem. Firstly, the hot water from the engine's flow circuit ought to enter at the bottom of the calorifier heater coil (if it's orientated in an up/down fashion) and return through the top one. If the heating coil connectors are horizontal, it doesn't matter. Also, the feed from the engine will be from the top (where the water will be at it's hottest). If you have a long circuit between the engine and the calorifier, you may have an air lock in the water circuit which the engine's water pump is unable to push through. Perhaps the engine isn't getting hot enough in the first place?

You have a small leak somewhere in the system. Check for dripping taps and puddles beneath sinks and so on. If you'ne not winterised properly, it's quite possible that teh pump itself is leaking.

This is because the pressure in your hot water tank is greater than the pressure in your cold water system and you're getting back flow. There's also a good chance that your pressure relief valve is gushing occasionally. The solution it to fit a non-return valve on the cold water inlet to the hot water calorifier tank or replace one if it's faulty.

Many older boats are piped with hose (often red and blue to denote water temperature). Over the years, the hot ones can become weakened by the water temperature and will sometimes bulge like a snake that's just eaten. These bulges are weaknesses that will blow soon with the result of the total loss of domestic water, possible cabin flooding and expensive emergency repairs. In truth, you should replumb the whole boat as soon as possible as if you've found one bulge, it's almost certain there will be others. Today's modern plastic piping such as Hep2o should be used as it's very flexible, easy to connect (and disconnect) and withstands expansion and contraction extremely well. We use Hep2o throughout all our installations.

A private boat should be sanitised at least once a year at the start of the season. We'd recommend using Aquatabs or similar products designed for the purpose of treating potted water. If you're not using and refilling your tanks regularly, you should consider sanitising more often.

Maybe. Not all hot water calorifiers have a port for these. If there's a port for it, it's relatively simple to fit, but can only be operated by shore power unless you want to enter the world championships for speed battery flattening. Shore power is an entirely different affair if you don't already have it and should only be fitted by competent electricians.

This happens because your domestic water pump can't cope with the demand for water. You might add or increase the size of the pressure vessel in the water system and/or increase the size / capacity of the pump. Or, issue strict instructions to the rest of the crew!

A pressure vessel, often called an Expansion Tank, stores water pressure that's built up by the water pump. When you open a tap, the pressure in the expansion tank initially pushes the water through the pipes. When this pressure drops, the switch in the pump senses it and the pump begins. The main advantages are that it increases pump life, reduces pump noise (as the pump operates less) and provides an even pressure throughout. The larger the pressure vessel, the better if you have multiple outlets.


Most electric flush toilets will have a fine gauze filter somewhere on the inlet pipe work to the loo. This is probably blocked. Check also any raw water filter on the sea-cock.
Probably. These often begin to leak because of physical damage to the flushing stack or its mountings. Spare flushing stacks can be purchased, but usually at considerable cost which is often not massively lower than the cost of a whole new toilet. Johnson and Jabsco toilets look very similar, but are subtly different and you'll probably find the parts aren't interchangeable. Also, Jabsco spares vary depending on the age of the toilet and there are, again, subtle differences between different models making it easy to order the wrong parts.
This is probably only a job that a boat yard can do unless we're talking about a portable loo. This is because only a boat yard will have the facilities to pump out a toilet tank. If you're getting unpleasant smells from a "Mansfield" or "Sealand" toilet with the large "ball" valve at the bottom of the china bowl, it's most likely that the seals are worn. These can be replaced.
Yes, but it's probably not a simple job. This is because your tank is most likely made of Stainless Steel which is a very hard material to work with, especially if it's in situ in the bilges of your boat. Tank senders will require you to cut a hole of about 70mm diameter to drop the sender into and secure to the top.

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