no hot water

[sox]

just fitted a shower pump to the expance pip of cylinder but now there is no hot water to the rest of the house. the hot water runs for about 4mins & the pressure is low

 

[grahamgas]

Must be an air lock somewhere, or your ball valve in the cold water cistern is stuck.

 

[sox]

put new gate valve on the cold feed from the cistern to the cylinder & feed cold water trough the hot water pips back to the cylinder for the air lock, still no joy

 

[Bernie2]

Perhaps the pump is using off the water off the hot supply and pulling air down the expansion pipe?

Did you branch into the expansion pipe or fit a bos on to the top of the cylinder for the pump.

Have a look at the Essex flange site.

 

[sox]

would this happen if the pump was conected to the main supply

 

[Gassy]

Is it a twin pump?

 

[WHPES]

Is it only a problem with the pump running?

Check supply pipe from DHW tank - is the gate valve fully open? Is it all in min 22mm pipe?

Reconnect to cylinder with Essex flange

 

[Toddyplumb]

As Bernie has already pointed out, if your pump is on the vent pipe (expansion) it is in the wrong place . It will pull the column of water down the pipe and will then let air in which it sounds like is giving an air lock, rather than pulling hot from the cylinder . Pump needs alternative feed I would guess

 

[sox]

thanks for all the tips on the hot water but the problem was a gate valve on the cistern was stuck closed. but now have anther problem can seem to get hot &cold water thrugh the pump to the shower. pump is not connected to the main supply

 

[oldplumber]

have aread of the instructions sounds like this pump was connected up correctly in the first place and they dont like being run dry either, screws them up somewhat

 

[sox]

sorry,i mean the pump not connected to the main electric yet

 

[WHPES]

Try connecting it up first.

Have you got the correct type of pump? (if the shower is above the tank height then you need a negative head pump)

 

[sox]

shower is not above the tank, but the water dose have a long way to go to the shower head

 

[WHPES]

Try it with the pump connected before you alter anything.

Is the pump positioned correctly (i.e. level or near to level with the bottom of the cylinder)? Have you used 22mm pipework for your shower pump feed and supply runs for both hot and cold? (not critical for low volume pumps (eg 1.5 bar) but if you have higher pressure pumps (2.5 bar plus) it is important)

 

[sox]

how can you tell if your pump is pull air from your expance pipe & if i turn off the gate valve at the tank to the cylinder & drain off the radiator at the lowist point would it then be possible to change a radiator

 

[WHPES]

Are you saying you have a primatic or direct cylinder (as opposed to indirect)?

An indirect cylinder has a separate coil inside through which the primary circuit runs, keeping the heating water separate from the domestic hot water.

 

[sox]

i don't no if it is a primatic or direct cylinder. also do you think it would be better to fit a surrey flange then have pump connected to the expance pipe.

 

[WHPES]

If its still a problem, then yes. However I would suggest an Essex flange as the apreture is larger. Put it as high up the side of the cylinder as you can before the domed top.

If you are wanting to change a radiator, look in your loft and see if you have 2 tanks. The smaller is for the heating circuit. See other threads about the subject - already covered in depth.

 

[sox]

there are three tank in the loft two large & one small tank

tested the pump, cold run ok but the hot run for about 5mins then stops could this be because i have fittered the pump 1/2 way down the expance pipe & not fittered a surrey flange

 

[WHPES]

Sounds strange. Are the two large tanks connected together or do you have two separate systems?

if it were a problem with the expansion pipe I would have thought the problem would be from the start and not just afer 5 mins.

Have you checked you aren't running out of water in the tank in the loft when the hot stops?

 

[Plumbstar Tom]

iv been in some houses with a normal F & E tank

then a CW tank for the hot cylinder and then another separate one for the cold feeds

 

[WHPES]

I've also seen two tanks, with one connected to the other by a 22mm pipe in the bottom and the one without the water flowing into it full of slime and fungus.

 

[Plumbstar Tom]

the ones i refer to were not connected, saw it on a few occasions

i have seen two tanks joined together as you mention, i often advise that both should have a ball valve to keep water flowing

 

[WHPES]

Should have the float valve in one tank and the oulet in the other to ensure freshness

 

[Plumbstar Tom]

yep but often they dont as one is just shoved on with a bit of 22mm and left like that

 

[sox]

the two large tank are connected together & i think there would not run out of water

 

[Plamber]

How long does it take for the hot water to start working again? if you switch it off then on again does it work at all or do you have to wait?

If there is no essex or surrey flange fitted it could well be pulling in air.

 

[sox]

i think my nexts step is to fit a surrey flange because it dose show a surrey flange in the diagram in the instructions. as anybody fitted a grundfos shower pump model stp 2bar pos head &did it need a surrey flange

 

[Plamber]

you will have to move the pump then, from what ive read you have fit the pump on the vent pipe

 

[WHPES]

If the pump is on the vent pipe (above the horizontal part from the top of the cylinder then that's your problem. If you are going to fit it to the cylinder outlet at all it needs to be from the horizontal part (the connection angled slightly downwards to avoid filling up with air when stood).

Like it has been said, it is usually actually easier in any cast to fit an essex or surrey flange than to start messing about with the outlet pipe.

 

[easyt]

iv been in some houses with a normal F & E tank

then a CW tank for the hot cylinder and then another separate one for the cold feeds

I have three tanks in loft. One for CH. One for Hot. One for cold to bath only (presumably to equalise pressure for mixer tap with combined shower.

 

[sox]

i have fitted it to the horizontal pipe coming out of the cylinder at a slight angle down to the pump