Problems after replacing a pump

[scott488]

Hiya Everyone,

This is my first post on here, so be gentle with me.
Well today I tried to replace a pump for the central heating and what I thought was going to be an easy (ish) job had turned into a bit of a mare.

To cut a long story short.....I had to remove the pump by draining the water out of the system and removing the cut off valves along with the pump, looks like it had been in so long that the valves were rusted in solid.

So I 've put a new pump in, turned the water back on, bled the radiators, bled the pump, but when the heating is switched back on the radiators dont heat up. When the pump is running the pipes around it get hot so I presume that it is doing its job, but somewhere along the way the hot water isnt getting to the radiators.
If I leave the heating on and open up the drain valve on the radiator downstairs, hot water starts to come from it, which makes me think that there isnt a blockage.

So thats where I am at.......

 

[gazthepottertonengineer]

check your F&E tank in loft the little one

is it emptying out when you drain down if not you have a blocked feed pipe from it to your system

 

[fireman22]

have you any motorized valves? are you sure all valves you may have closed are open? on front of pump there is chrome screw take it out while pump is running, if you touch a small screw driver inside you should feel it rubbing against spinning pump( a small amount of water will come out so put a towel down) if it is spinning put screw back in then it prob is an air lock.

 

[scott488]

Cheers Gaz.....would the radiators still be able to be refilled if this was the case.

Only asking cause they seem to be bleeding ok.

If the problems is with the feed to the system from the tank, what can be done?



Fireman......what do the motorised valves look like, the only ones i have touched are the main water supply into the house and the ones either side of the pump?

 

[kevplumb]

top may be a different colour

 

[scott488]

Kev...there are two things that look similar to that picture (made by sunvic...with power cables going to a junction box), but these havent been touched by me.

And checked the pump and it is spinning........does this look like it is an airlock and if it is, what is the best way to clear this problem?

 

[kevplumb]

if they have levers on the sides/end they should be open when you fill up

usually marked man/auto


these them ?

 

[scott488]

Doing a quick search on the net, these two "things" are:

Motorised Valve Actuators 2 port...........Sunvic SZ1301

There are no levers that i can see....

 

[kevplumb]

have you got both water and heating switched on ?

what speed is the pump on ?

is the boiler firing for long ?

 

[scott488]

Yes I have had both water and heating on at the same time....

I tried the pump on all three positions on the switch

The boiler seems to be firing ok, if I put the heating & water on constant, then it goes for ages

 

[kevplumb]

cant find the sz 2301 on sunvic site sz number is the motor

try and switch the water off but leave the heating on sounds like air

make sure the pump is in the right way round

 

[scott488]

Its the SZ 1301, if that makes any difference......

How will I know if the pump is the right way round?

If it is air, how do i solve this?

Cheers for the help by the way!

 

[kevplumb]

arrow on pump body should be pointing away from the boiler and towards your valves

 

[scott488]

The sunvic valves we mentioned i take it?

 

[kevplumb]

yup your learning