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We have a stored water system for our hot water which means we use a water pump to give the hot water enough pressure when mixing with the mains pressure cold. We had a Stuart Turner for many years which finally gave up towards the end of last year.
We were recommended a Salamander CT Force pump as a good replacement that would also be quiet. This is important because the pump is in the airing cupboard in the same room I use as an office. I spend a lot of time in Teams and Zoom so don't want a noise pump interfering all the time.
Pump fitted by a professional plumber and it was immediately obvious that it was very noisy- you could hear the pump kick in when you turned the hot water from pretty much any room in the house.
Contacted Salamander directly and they had a list of questions for the plumber about the install which he kindly sent them. Salamander sent a replacement pump.
The plumber fitted it but it was no quieter. I contacted Salamander again and they agreed to send one of their engineers to loo at the pump and repair/replace as required.
He turned up and said he didn't like what the other plumber had done and when asked why he pointed out that one of the flexies was slightly twisted and the thermostat on the hot tank was set high at 58 degrees. Straightening the flexy and turning the thermostat down to 50 made no difference to the noise. He just said that the claims about the pump noise were based on ideal conditions and we had floor boards which weren't ideal. He then declared everything fine but left another replacement pump 'in case you want to try that'.
Salamander consider the case closed as the pump fitted has been passed as okay by their engineer. Apart from trying to sell the two spare pumps to recover the purchase price what can STW suggest?
Do you know of a very quiet water pump that is actually quiet when installed in a house with floor boards?
A Stuart Turner given that you were happy with it for years?
Or pad around the pump with squirrel pelts.
50C too low, no idea why he would turn it down to that. 60C should be the setting, perhaps even plus a couple of C to account for any inaccuracy and to error on the side of caution.
Is it the pump itself that's noisy, or the vibration that it's transmitting to the floorboards? If the latter, could you not mount it on some resilient mounts to isolate it from the floor? If it's the pump itself, some noise insulation around it? It won't help airflow, but it's not running continuously so should be ok.
Ok
Fyi i have pumped millions of gallons of luquids over the years so know a tiny amount about pumps
Options. Send all pumps back to Salamander and get the RP50t as its the quitest pump they make
Mount pump on a decent heft of rubber matting maybe 20cm
Isolate pump with long braided flexi hoses 30cm
Grommet the mounting for the pump
See if an inverter motor is available to drive the pump giving a soft start, some are rampable and this may help
Dropping the hw is strange, i suspect to stop cavitation, which is noisy but no domestic hw systems should run that hot
Other suggestions, try a small combu boiler ch pump, but i dont know if theses will offer enough pressure but they are quiet fo sure
Box in the pump, once isolated on rubber, i dpubt it runs long enough to overheat but some airflow is needed
change to a mains pressure cylinder, no pumps!
I tried screwing hardboard into the floor joists through the floor board, a layer of foam rubber flooring tile and a top layer of hardboard but no improvement.
Apparently hot water should never be above 60 and these pumps are only warrantied to 65 degrees
Having held the pump while running to damp the vibration it seems it is the actual noise of the pump itself rat=her than secondary vibration and placing it on a separation layer from the floor having no effect supports this.
Stuart Turner pump is the tempting option as it is probably cheaper than replacing the existing system with a combi or whatever.
I have considered trying to box it in but building a properly sound proof box with also stop any heat loss or ventilation for the pump which seems a bad idea.
Please keep your suggestions coming though. Stuart Turner pump is head of the queue at the moment
Dont fix directly to the floor boards.
Get a vibration mount, and fix indirectly to the floor.
Your plumbing looks like it is touching the shelf, fix that.
Your rubber sandwich had screws going through straight the hardboard into the floor, they will transmit the sound. I managed to make the pump in my campervan almost silent by wrapping foam completely around an upright, and then using 14mm zip ties to secure the pump around the upright. At no point do the zip ties touch the upright, there is foam all the way round. It's much better than the rubber isolation mount that came with the pump.
Alternatively, to you could screw the pump into a much thicker block of rubber, and loose the hardboard.
Get some longer flexy pipes so you can put a loose loop into each to reduce vibration to the pipes.
PS Your hardboard also looks like it is touching the timber the electrics are mounted on.
All the above plus if you end up with a laminated mount bond it with silicone or CT1 rather than screw it together/down.
Good luck, it would drive me mad too, especially the bit where they sign it off because the tickbox test was passed rather than the problem resolved.
Try this, its 30.second job
On the outlet side there is an isolation valve, put a tiny amonut of turn on it to reduce the flow
Centrifugal pumps like to run under load so a bit of back pressure may smooth it a little
And your soundproofing might be making it worse. 3 rubber companies in soton, Martins rubber is one, the other is over the itchen bridge, fork left, past chippy, turn left onto main road, 1 ind est on rhs, amd one down by st marys gasometer near the chinese wholesaler, concrete factory, portmere rubber
I'd look at mounting that on some proper vibration damping feet. Something like these:
https://www.avindustrialproducts.co.uk/products/cylindrical-bobbins#Male-Female
https://www.gelmec.co.uk/product/?cat=sandwich-and-stud-mounts&family=silicone-gel-stud-mounts&ty=10
If it was me, I'd screw a thick board to the floor to create a secure base, mount those anti-vibration feet using screw-in threaded inserts on the base & then mount the pump on those.
If you have to make a sound-proofed enclosure for it, you could always ventilate it with some PC fans to prevent over-heating?