Replacing Central Heating Pump

[cocoots100]

Hi There

The circulating pump on our central heating sysytem finally gave up the ghost this morning in spectacular grinding, noisy fashion, followed by a burning smell. Just wondering how easy is it to replace - is it just a question of the two pump valves above and below and swapping it out? Just wondering if it is that easy or am I opening a potential can of worms in doing it myself. None of the local plumbers want to know at the moment and it is getting a tad nippy out there.
Any help would be much appreciated.

 

[Softus]

There are losts of topics covering this, but, basically, it will one of several ways:

1. You buy an identical pump and swap the bodies (you can't expect to do this with every model), and the valves hold up.

2. You swap the entire pump for an identical one, and the valves hold up.

3. The valves don't hold up, and you end up having to drain the system (or most of it), and you fit new valves.

4. You fit new pump and valves, but the distance is different, and you have to alter the pipework.

5. You do one of the scenarios involving valve replacement, and you stand back in amazement, then, when you refill, nothing happens, because there's a blockage in the cold feed. You cut the cold feed near the tee, and sweat and swear because it's hard to get at, clear the blockage, reconnect, refill, vent, and emerge triumphant with several shiny new synapses inside your head.

6. As per 5, but you forgot to add inhibitor, and months later your rads start to spring pinhole leaks.

7. As per 5, but you remember to add inhibitor, and to clean out the system first, but the system was badly corroded and weeks later your rads start to spring pinhole leaks.

8. You get a heating engineer to do it all.

BTW, when you vent - do it with the boiler and pump switched off (i.e. turn everything off at the programmer).

Oh, and the same applies to working on the pump's electrical supply.

 

[ChrisR]

Also - though you may get a spanner on the big nut, they are inclined to seize onto the pump. The valve will turn inside the nut - and leak a lot. I have failed to undo one of these nuts when using 2ft long spanners, because it is hard to hold the pump still. Can be best to break the nuts or remove the valve(s) with the pump. You can't always get a big spanner on the nuts.

Quarter-turn pump valves always always leak from the stem unless new.
Pump valves which look like gate valves without wheelheads, will often not turn off however hard you do them up. If you overdo it they can break and stay shut forever.

Even new valves of the same basic design may be different lengths.
Some old pumps were different lengths, packing pieces are available.
Remember pump shafts must be horizontal or they'll wear very quickly.

Job can take anything between 10 miutes and a day, with, as Softus says, a legacy.

 

[Soggy_weetabix]

The nuts ( or unions to be exact ) will squash upon pressure and you will probably need a decent heating engineer, as this is at best an experienced DIY job.

I will saw the unions off if they wont budge but I have experience if the valves dont hold.

Basically, some plumbers seem fit to install a pump and...
1: smear boss white on the washers
2: tighten the unions to the point that arnie wont be able to undo them in 6 months.

Just over hand tight and loads of silicone gease on the thread of the pump make for an easy change in future,

 

[Softus]

Just over hand tight and loads of silicone gease on the thread of the pump make for an easy change in future,

Hear hear!

 

[breezer]

a whole bunch of plumbers / heating engineers and they forgot one thing, if you do "go for it" put an arrow on the floor / wall showing pump direction, and put new pump in same way.

i learnt that from this site

 

[bab]

Noboddys mentioned tapping the nuts loose with a hammer & sharp cold chisel while ya mate holds the pump. good 4 stress & bad 4 nerves. Or am i the only ****** here.

 

[Softus]

Noboddys mentioned tapping the nuts loose with a hammer & sharp cold chisel while ya mate holds the pump. good 4 stress & bad 4 nerves. Or am i the only rufarse here.

No - it's because we don't have any mates

 

[oilman]

That's funny, neither do I.

 

[bab]

All right i give in . he's not a mate its the £500 + a week he cost me that makes him keep comming. I only have mates when they need plumbing doing. When its done so are they. KNOW WHAT I MEAN. Old saying ( a friend in need is a pain in the arse.)

 

[allesklar]

I got a plumber to do this as it was a rented property and I didn't fancy my chances as both valves on either side of the pump had seized onto the pump despite using a cold chisel to try and move the nuts .

The plumber used a couple of rubber cones to close the feed to the central heating and the expansion pipe at the central heating header tank.
Then he opened the Central Heating system drain valve to reduce any internal pressure.Very little water came out! He was able to release one valve nut but the other remained solid.So he just removed the 22mm valve nut from the copper pipe and replaced the valve complete.There was once again hardly any water leakage.The pump was replaced without any problems. He explained this by comparing it to a straw dipped in water and then putting your finger over the top end so that the water won't run out.

 

[expertgasman]

Over 5 years after last post! Must be some sort of record! lol

 

[mike42]

Over 5 years after last post! Must be some sort of record! lol

And another four years but a superb thread! How did Google know?