How to pressurize a water system

[All_at_Sea]

I've had to take out the immersion tank to fit a new element and now it is all back in place the pump is running continually, presumably because the water drain down has de-pressurized the pressure tank. I've located it and found the nozzle. Can l use a bicycle pump on this to pump it back up or does it need a special kind of pump? What amount of pressure do they require or psi (as this is what my pump works in l think)

 

[PCUK]

Usually a car foot pump fits and the pressure should be a little above the pump cut-out pressure but it's not critical.

 

[NormanS]

I've had to take out the immersion tank to fit a new element and now it is all back in place the pump is running continually, presumably because the water drain down has de-pressurized the pressure tank. I've located it and found the nozzle. Can l use a bicycle pump on this to pump it back up or does it need a special kind of pump? What amount of pressure do they require or psi (as this is what my pump works in l think)

Presumably the "pressure tank" that you have located, is an accumulator. It stops the pump from switching on and off when you are drawing water. (Cycling).
If your pump is running continuously, the more probable reasons are, that the supply has been turned off, or is empty, or has an open end, or a leak. It will take a little while to refill the calorifier. Have you given it long enough to do this?

 

[superheat6k]

Sounds like air in the pump needs venting. Simply allow the pump to run through open taps hot and cold for a few minutes.

There are two types of accumulator - with or without a bladder. With has a central joint where the bladder is fixed.

Without just drain with the vent open and pump off then the water pressure will load it.

With about 8-15 psi top charge through the schraeder car tyre type valve.

But I can't see how changing a heater would affect either option.

 

[All_at_Sea]

Good point about the calorifier re-fill time, not sure, will check today. I assumed that having drained the water to take out the calorifier l would have de-pressurised the accumulator tank? It does have a valve on the top, so l will check the pressure. Water is coming out of the taps but the pump is constantly on. Maybe l should leave them all to run for a couple of minutes to see if it does it automatically.

 

[vyv_cox]

The accumulator in itsef has no effect, except to reduce the operation of the pump, unlesss it is leaking of course. My boat didn't have one at all for the first ten years of its life. I suggest you turn off the cold tap and open the hot until you are certain there is no air in the water. Then turn off the hot, which should stop the pump. If it doesn't stop there is probably a leak somewhere or possibly debris in the pump valves.

 

[All_at_Sea]

Solved it by running the taps for two or three minutes, absolutely fine now, however the pressure relief valve is now leaking, the one on the tank itself! I'll have to take the whole thing out again.....

 

[simonfraser]

Solved it by running the taps for two or three minutes, absolutely fine now, however the pressure relief valve is now leaking, the one on the tank itself! I'll have to take the whole thing out again.....

the joys of a complicated plumbing system / boat ....

 

[oldsaltoz]

Quote: however the pressure relief valve is now leaking, the one on the tank itself!End Quote.
Is this the air valve used to pump the system pressure, or the one on the hot water tank?

The air valve is a simple replacement, just make sure the seal seat is clean inside the stem and on the valve.
The hot water system pressure valve should be flicked shut, not gently lowered, by flicking it shut you hace a better chance of knocking off any calcium build up on the valve seat.

Good luck and fair winds.

 

[David2452]

Solved it by running the taps for two or three minutes, absolutely fine now, however the pressure relief valve is now leaking, the one on the tank itself! I'll have to take the whole thing out again.....

Make sure you match the TPRV like for like, they come in several "blow off" pressures, however it is sometimes unnecessary to drain the system if it is located at the top of the cylinder, unfortunately this is often not the case with marine calorifiers. There is a correct way to match the accumulator to the actual (as opposed to advertised) pump pressure. I have posted it before on here, rather than a link I have included it below.
It is a fairly simple procedure but a helper at the tap end helps a lot. With the pump off and taps open set the pressure to about 5 psi, then close the taps and turn on the pump, when the pump cuts out turn on the tap just a dribble, immediately the pump cuts in turn off the pump and taps. Check the pressure in the accumulator which will be the cut in pressure. Pump off and taps on, the accumulator pressure will drop to the 5 psi you set in stage 1, now pump up the accumulator to just below the pressure you measured as the cut in pressure. It takes very little time and makes sure you get the best from the accumulator. The smoothing out provided by an accumulator (the bigger the better) is just one advantage but it also reduces the number of times the switch operates and extends it's life.

 

[All_at_Sea]

Quote: however the pressure relief valve is now leaking, the one on the tank itself!End Quote.
Is this the air valve used to pump the system pressure, or the one on the hot water tank

There is a pressure relief valve on the calorifier tank with a pipe leading into the bilge. It clicks when turned slightly and this sends water out the pipe, l've assumed it is a hot water relief valve to prevent over pressure in the tank. It leaks slowly so l am assuming something has got into the valve seat/mechanism so it will have to come out grrrrr.....!