Problems with Salamander pump

uknick

Will an airlock on the hot supply of a shower pump cause the bearings to fail? Before they failed, I never noticed any lack of hot water whilst using the shower.

About 20 years ago, I had a Salamander pump installed by a plumber and for about 17 years it worked fine. About 3 years ago the bearings seized due to a seal leak causing a limescale build up. I assumed this as when I took the end caps off I could see lots of limescale around the bearings. Not particularly upset as I thought 17 years was pretty good for a pump to last.

I replaced it with another Salamander pump, CT50+ Xtra. However, this only lasted just over 3 years before the bearings seized. I spoke to Salamander as they offer a 3 year warranty, but found out this is only valid if installed by a plumber. As I installed the new pump there was no warranty for the 3rd year.  

Thinking the pump might have been a one off faulty pump, I bought another Salamander and installed it. It failed with seized bearings after about 2 months. I got it working by exposing the motor shaft and freeing it with a spanner.

I put it back in and it worked for about 6 months albeit with very noisy bearings. But, these failed for good last week. I've got a replacement on order under warranty from Screwfix but before I install it I'm now thinking my pipe work may have developed a fault.

The pump has a separate feed from the cold water tank and a Wessex flange for the hot supply. Both these were put in by the original house builder, albeit without a pump.

On the hot supply there is a bottle air vent in the loft. The hot supply to the shower goes down about a 1.5m to the pump from the flange and then up about 2.5 metres to the loft, across the loft about 3m and then back down about 1 metre to the shower valve.

The reason for the vent valve; I've owned the house from new and when I moved in the shower would get an airlock after a couple of uses. When I complained to the new build site office (luckily they were still on site when I moved in) they came along and added the vent. As I was none the wiser at the time, and it worked, I thought nothing more of it. Since the vent was fitted there have been no airlocks in the shower valve. i.e. the water comes through, albeit not great without the pump running.

When the latest pump seized after only a couple of months I had a look in in the loft and noted the vent valve had evidence of limescale round the bleed screw. Thinking it may have developed a fault and was not letting the air out I changed it before I tried the latest pump again after freeing the shaft.

I’ve tested the unassisted water flow on both supplies and it’s in excess of the 2 litre per 30 secs recommended for the pump; cold is 3 litres, hot 2.5 litres and combined 3 litres.

Is there anything else I should check before installing the new pump when it arrives?

I’ve googled Salamander pumps and bearings and there are cases where the bearings have failed prematurely. But, if it happens again and I call out a Salamander engineer under warranty I wanted to check if I am missing something obvious.

EssexExile

There isn't a one-way valve in the pipework anywhere is there? We had a pump leak, similar age to yours, I replaced with a spare and that leaked fairly soon after. My plumber then replaced it with a different type and took out a non-return valve because the instructions told him to. Evidently they cause a build up of pressure in the pump. I ask because the problem that the non-return valve was supposed to cure was air in the pipes.

uknick

EssexExile said:

There isn't a one-way valve in the pipework anywhere is there? We had a pump leak, similar age to yours, I replaced with a spare and that leaked fairly soon after. My plumber then replaced it with a different type and took out a non-return valve because the instructions told him to. Evidently they cause a build up of pressure in the pump. I ask because the problem that the non-return valve was supposed to cure was air in the pipes.

Not that I can see.  If there is, it would have been put in by the original builder all those years ago and I can't see why they would have hidden it away (but who knows on new builds ).  But, your comment is really helpful, because I had mused about putting a non return on the hot supply.  Now, I've scrapped that idea.  Thanks for saving me a lot of hassle.

The plumbing is pretty simple apart from the vent on the hot supply in the loft. All that I have changed on the original shower plumbing was to replace the original gate valves with lever stopcocks, in exactly the same place.  But that was some years ago and the original pump worked for some time after that before it failed.

nofoollikeold

Have you checked the temperature of the hot water? Salamander specify this as a maximum of 60 degrees.  I've had problems with shower pumps (not Salamander) where tenants have set hot water temperatures much higher than 60 by fiddling with the thermostat.  

uknick

nofoollikeold said:

Have you checked the temperature of the hot water? Salamander specify this as a maximum of 60 degrees.  I've had problems with shower pumps (not Salamander) where tenants have set hot water temperatures much higher than 60 by fiddling with the thermostat.  

Sorry, I knew I forgot to mention something in my original post.  I did check the temperature and it was just over 50c at the bath hot water tap after running it for a minute or so to ensure the maximum temperature was reached.  Bath taps are only about 3m from the hot water tank so I wouldn't expect too much of a drop in temperature.

My gut feeling is the bearings failed due to a design problem.

I'll wait to see if there's any other feedback from here over the next couple of days.  If nothing is forthcoming to identify a plumbing problem I'll install the replacement, register it for the warranty and see what happens.  If it fails again under warranty, I'll call out Salamander engineer and get them to check the system.  If they do find something wrong with the plumbing and I have to pay for them to fix it, at least it'll be done.