Central Heating pump too hot???

[phil_stacey]

Hi,

Can someone advise.

I have a conventional wall-mounted bolier in a 4 bed detached house. Both house & boiler are 16 years old... The pump in the system is brand new (less than 2 weeks!!) however, when the system is running the pump is VERY hot to the touch. The person who replaced the old one made the comment when they did it that the old one seemed to be running too hot...
This has the effect that after the system has been running for a while it will cut out with a loud 'CLUNK'. Then, when it tries to kick in again it will almost immediately do the same. Again I was told that this was due to the bearings in the pump seizing up because of the heat inside the pump. If you leave the system off and let everything cool down for a while it will work again until it seems to over heat.

My question is what is making the pump too hot. Is it running too fast/too slow? If so, how can you change the speed? Is the thermostat on the hot water tank set too high (incidentally what should it be set to?)...
...
Or is the boiler just knackered and causing excessive heat??

any assistance/advice would be much appreciated,

thanks

 

[breezer]

1 & 5 would help here

 

[Kristoflampie]

Pumps are designed to cope with a lot of heat in normal use central heating systems but if they are pumping against a restriction or a greater head than they are capable of moving they will heat up and possibly thermally trip internally if one is fitted. Also they have to be fitted correctly as the bearings are usually water lubricated, so a domestic central heating circulator has to sit with the head horizontal and be vented properly to allow a tiny bit of water to lubricate it or dry surfaces rub whilst its rotating and again it heats up..... Hope this helps, good luck.

 

[ChrisR]

Hopefully its new(?) valves work so turn em off, undo the 2 or 4 allen type screws and have a look inside. May be full of sludge.

What make is the pump? Wasn't aware of any thermal cut-outs.