Central heating advise please

polo2k · February 13, 2012, 07:05:37 PM

Hi all.
I was sat here today thinking it was a bit nippy, gave the heating a poke, and realised the burner wasnt staying lit (indicating that the stat was hot enough), decided to go check the diverter valve and that seems to be happy enough, then checked the pump.

Firstly, it appears that stevie wander is an electrician in his spare time:

So I decided that poking about in there was a bad idea and got the cover off the pump. checked for volts and found 230AC across L & N, with the pump not running.

By the process of deduction, im guessing my pump has expired (what a time for it!)
There is an isolation valve above and below the pump head, am I right in thinking that I can lock these off and then just swap out the pump without a drain down? Will the pump self prime?

Cash is tight so an engineer isnt really an option at the moment, and its getting chilly!

Any advise would be grand!

heres the pump

oscar · February 13, 2012, 07:09:20 PM

I'm no plumber but I DIY. There might be a bleed screw on the new pump but if not, it should self-prime as the mains pressure will fill it up.

Tank · February 13, 2012, 07:18:09 PM

Yes, it will be fine running the pump for a short period with no water. Fingers crossed that the pump is the problem.

4x2 · February 13, 2012, 07:23:38 PM

Quoteam I right in thinking that I can lock these off and then just swap out the pump without a drain down?

I would say yes, any air left in the system will end up in the rad furthest away, a quick bleed should sort that. I should warn you i'm not a heating engineer, but i would suspect the pump given what you've said... is there any way of testing it before you remove it ?

Alex · February 13, 2012, 07:36:53 PM

Hi,

No expert myself but since moving into our house I've had to replace 3 zone valves but never the pump. Do you get hot water? Or is that on a different system?

I think Stevie wired up our 'lectrics as well.

Alex

Bikeracer · February 13, 2012, 07:41:27 PM

Get a biggish screwdriver,place the end of the handle to your ear and press the blade end against the pump body,you'll be able to hear if the pumps running.

The two valves will isolate the pump and you should be able to undo the two large union nuts and remove the pump.From memory the mating faces are flat with a sealing gasket between.

Get an old towel or sheet or something ready to catch the small amount of water in the pump,by the time you've undone the bottom nut the pump will more than likely be empty anyway.

Note the direction of flow,usually marked with an arrow and if the plump is faulty take it to your favourite plumbers merchant to check for size against a replacement.

Not complicated job at all,just make sure the faces of the old joints are clean from any stuck sealing washer,might even be a rubber gasket.
A replacement pump should vent itself in that vertical position,but don't be tempted to run it dry,the water lubricates the bearings.

Allan

polo2k · February 13, 2012, 07:49:16 PM

Wow, thanks for all the advise guys.

I used to be tech manager in a catering spares company (if anyone is in the trade, a large BS669 pt2 hose supplier, pm me with guesses

)so I used that knowledge and applied it to the system with a bit of logic.

I powered down the whole system for a bit and then pulled the motor tail cover off, underneath there is access to the shaft and it has a phillips end on it. spun it by hand, and I appear to have got it going again. Ive not got the speed up to full to reduce the risk of a motor stall, when the weather is better I may change the starter cap in case thats getting a bit dodgy.
For the moment though, the rads are back on and the cars are on them (they had started to sleep under the duvet covers instead of on them lol)

Ive got a spare 3 port valve, just in case, looks like ill need to keep an eye open for a pump now

PHew Panic over and ive freed off the isolating valves just incase I need them soon !

polo2k · February 13, 2012, 07:51:34 PM

Allan, im guessing from your username its the same way you would listen for ending noises (ie. mechanics stethesscope)

Are you in the trade btw?

Bikeracer · February 13, 2012, 08:08:54 PM

Served my time and did seventeen years plumbing but not done any for more than thirty years or so now,it wasn't as well paid then as it is now.
You sometimes see water board workers with a long rod with what looks like a plunger rubber at the end,thats for his earhole when he's listening for leaks.

Now you've mentioned it,there was sometimes provision for freeing a stuck rotor as you found, and if memory serves, that big brass screw is to vent the pump if it's fixed in a horizontal position.

My username is from racing 1/5 scale R/C GP bikes .

Allan

Bikeracer · February 13, 2012, 08:20:31 PM

Bugger,got carried away typing and forgot about some wagons and coaches I was watching on ebay,both lots went cheap. :'(

Perhaps as well,I've spent far too much recently anyway and there's loads of other stuff I'm watching.

Allan

OwL · February 13, 2012, 08:27:07 PM

Hello mate, If you need a new pump look at Plumbase, Link below:

http://www.plumbase.com/branch_finder

Best of luck mate.

polo2k · February 13, 2012, 09:07:33 PM

ta!

hairygit · February 13, 2012, 10:31:24 PM

Before you part with your hard earned cash, the large round silver screw on the end of your pump, remove it and you will see a srewdriver slot in the end of the pump spindle. With the heating turned on, and the thermostat set to maximum, try putting a screwdriver in the slot in the end of the spindle and turning it in the direction of the arrows on the pump body (looks like anticlockwise in your photo), as these are induction motors, they have no brushes, work on magnetism alone, and sometimes scale etc builds up and they need a helping hand to start. My plumber mate showed me this trick many years ago, and he made easy money for his £50.00 call out fee!

Alex · February 13, 2012, 10:37:18 PM

Glad everything is up and running again.

Pete Mc · February 14, 2012, 10:19:45 PM

I'm a fully apprentice trained plumber,even though I currently work as a bus driver(damn recession,grrrrr).
There is lots of good advice on this thread,however,if you are having to start the pump with a screwdriver,the indications are that the.pumps bearings are about to fail meaning a new one is required.A new one is only about £40 so just change it and forget about it for a.good few years.Normal life expectancy for a pump is around 15 years before they start to wear out.
As has already been mentioned by yourself and others,isolate the pump byvturning off the isolators,then get a large pair of pump pliers on the main nut,then holding the isolation valve so it doesn't turn with the pump when you begin to exert force.If it does turn,then you will be looking at a partial drain down in order to remove the isolators to remake up the joints with boss white.It will leak if you allow the valves to turn,trust me.
Once the pump is removed,use wes and dry or wire wool to clean up the faces on the isolators or they too will leak due to not having a flat face.Do not use any jointing compound on the rubber or fibre washers either,this can cause compund to contaminate the pump bearings which will cause premature failure.
Once fitted,turn on the valves and remove the centre screw to vent the pump head,then switch it on.If you want,instead of renewing the cable from the terminal blocks,just cut through the cable near the pump,remove the insulation and on most pumps,the terminal connections are of the crimping type,ie push a spring loaded bit,insetr unsheathed wire into the hole then release.Connection made.
Don't worry about the mish mash wiring too much,this style of central heating wiring is just to save money on the generally recommended wiring centre,which usually cost about £35,as opposed to the tree quid for a large terminal block.
Hope this helps you further.

Pete