Loud Grundfos Recirculating Pump

[IanCun]

Just a quick disclaimer... I know nothing about plumbing... but I'm keen to learn!

I've recently moved in to a new place and we can hear a loud pump sound whenever we run a hot water tap/shower. It's a thump....whirr sound (with the thump happening every 10 secs or so). I took a look in the garage and found the sound was coming from a Grundfos pump.

We had a plumber round to give a quote on fixing the problem, but he said it was a recirculating pump so that we can get instant hot water. At first he thought it was something used instead of an expansion vessel. Apparently we can just turn the pump off and it should solve the noise problem - although means we have to wait longer for hot water.

Is there anything we can do to reduce the noise? It's directly under a bedroom and there's no way to sleep if someone runs the hot water at some point during the night.

 

[IanCun]

Just as an update... I tried turning the pump off, but it really reduced the water pressure on the taps (so low that a shower would be a no-go).

 

[SimonJohns]

It's not a recerculation pump

Get a different plumber for a start.

Second of all it sounds like a booster pump of some kind. I can be specific as it is a Grundfos and they have made more pumps than there are rats in the world

Do you have any photos or model numbers.

Photos will be better as there may just be a simple install fault

 

[IanCun]

Thanks for the reply. Photos as requested 🙂

I've taken some of the airing cupboard, in case that helps identify the type of system. The noisy pump is the large one in the 2nd photo.

 

[SimonJohns]

Wow you must have a large house

You defiantly have a boosting pump.

Do you have tanks/cisterns in your loft?

You can have flexible connections onto and off the pump to help reduce noise

You can also raise the pump slightly and put a special mat underneath to also help lower the noise level

It will also be worth having a good plumber give the pump the once over. The bearings may be on the way out causing noise

 

[IanCun]

I've not been up in to the loft yet as we've got tall ceilings in the loft hatch room and my ladder can't reach, so I can't answer your question unfortunately. From what I can tell, the pump is 7 years old.

It's the "thud" every 10 seconds or so that is the main the problem - is that the usual operating sound?

I'll mention about having a mat installed underneath and the flexible connections. Is there a special name for the mat, or is it something that should be familiar to plumbers?

Is there anything quieter that I could fit instead of having this pump, or is it something I'll have to live with?


BTW - do you know why there could be two boilers? Will they just work in tandem to heat the water, or is one a backup?

 

[SimonJohns]

The 10second start will be due to a leak or faulty check valve in pump

The mat is comman but will only come for specialist plumbing supplies

You won't find many plumbers that a familiar with this type of work. Or competent.

The reason for the two boilers could be.
They don't do a boiler big enough for your house/ the last homeowner didn't want to rely on one big boiler. But two smaller ones.

My best advice to ensure a long boiler life is to have one thermostat set higher on one boiler than the other. Alternate this setting twice a year

 

[IanCun]

Thanks, it sounds like this could be harder to fix than I first thought.

Any tips on finding a plumber that could tackle something like this? (I'm in South Manchester).

 

[SimonG]

I like to bolt the pump to a nice heavy paving flag and then use a sheet of soundproof under the flag.



[DLMURL="http://www.keepitquiet.co.uk/vibration_pad.html"]anti-vibration mat to reduce vibration from appliances[/DLMURL]

 

[SimonJohns]

Use anyone you want. But get a quotation before hand.

The is a forum on here you can post on.

Looking for a plumber. Sorry cant post a link. Im on my phone

 

[chris watkins]

Hi Ian
You have A Grundfos MQ3 booster pump feeding an un-vented hot water system both have expansion / pressure vessels within them these need testing & re-presserizing from time to time (the un-vent cylinder should be serviced once a year with the boilers). If these are flat it can lead to noise when in operation.
Make sure the plumber you employ has both the un-vented ticket & is experience with larger boosted water systems.

 

[IanCun]

Big thanks to you all for the help here - joining this forum has been HUGELY helpful.

Out of interest, how would I stop the hot water on this system? Would I need to use one of the gate valves, rather then just relying on the cold stop-cock?

Hi Ian
You have A Grundfos MQ3 booster pump feeding an un-vented hot water system both have expansion / pressure vessels within them these need testing & re-presserizing from time to time (the un-vent cylinder should be serviced once a year with the boilers). If these are flat it can lead to noise when in operation.
Make sure the plumber you employ has both the un-vented ticket & is experience with larger boosted water systems.

Thanks Chris, that's given me something to help find a plumber that will be able to sort it. I checked the red pressure vessel next from the first photo and it reads 0.5 Bar - not sure if that indicates anything.

 

[SimonG]

It's the gate valve on the horizontal pipe that goes into the pressure reducing valve and then feeds into the bottom of the unvented cylinder.

The 0.5 bar is the current pressure on your heating system, I would think it should be nearer to 1.0

 

[chris watkins]

No, red one is for the heating & nothing to do with booster or hot water but likely that 0.5bar is not enough for heating system, how many floors of the house above the red vessel??
Both the H & C are shut down using the stop valve next to the tun dish, below the red vessel, unless there is another valve on the hot water outlet of the cylinder.

 

[chris watkins]

Sorry Simon the gate valve looks like it is on the balanced cold water connection from the combination (PRV) valve to me ? the one facing downwards (outlet) looks like the cold feed to me??

 

[SimonG]

Sorry Simon the gate valve looks like it is on the balanced cold water connection from the combination (PRV) valve to me ? the one facing downwards (outlet) looks like the cold feed to me??

Good spot Chris, didn't see it for the tundish. Would say should gave gone to specsavers but my new lenses are ready at the local opticians (for the last 10 weeks 🙂 )

 

[IanCun]

Cheers. It's a 3 storey house with the cylinder in the middle.

I've added a post to the "looking for a plumber" section, so will hopefully get some NW plumbers seeing this once it's approved.

 

[chris watkins]

Go get em quick :shades_smile:

 

[chris watkins]

Heating pressure should be OK between 0.5 & 1 Bar as there is likely to be around 5 Metres of water in the heating system above the vessel (1 Metre = 0.1Bar).

 

[IanCun]

Hmmm, the thread I posted in the looking for a plumber section doesn't seem to have appeared yet - I guess it's still in a moderation queue for the time being. If any NW plumbers spot this thread and can quote on it, please PM me 🙂.

 

[IanCun]

Hi folks, just a quick update.

I've had someone round who seemed to know a lot more then the previous plumber, and he didn't seem to think that the pump stopping and starting every 10 seconds or so was unusual (or that the pump itself was too loud). He's going to quote for adding flexible pipes and mounting the pump properley (estimated about £50 parts and a days work).

While he was there, he took a look at the cylinder and I mentioned that the tundish was dripping every other second, so he's going to take a look at a few of the valves to see if there is a leak.

He happened to lift the lid of the cylinder and noticed that the expansion vessel felt wet - there was condensation all over the lid too. So he thinks that there could be a leak somewhere on the cylinder and it may need replacing, as it should be bone dry. It looks like there may have been a leak at some time previously, as there is some staining on the ceiling under where the cylinder is. I looked at the expansion tank on top of the cylinder and happened to notice that the date says "2011" on it - but the cylinder was fitted in 2005, so I guess that some previous work has been carried out. The house was rented out while the previous owner had it, so I don't even know if he's aware of this - but I'll try and find out.

Should the MQ3 booster pump run when I use even a tiny bit of hot water from a sink tap? I would have thought that it was only needed when large volumes of water were required?

Hi Ian
You have A Grundfos MQ3 booster pump feeding an un-vented hot water system both have expansion / pressure vessels within them these need testing & re-presserizing from time to time (the un-vent cylinder should be serviced once a year with the boilers). If these are flat it can lead to noise when in operation.
Make sure the plumber you employ has both the un-vented ticket & is experience with larger boosted water systems.

Just so I understand in a little more detail, do you mean that both the pump and cylinder expansion vessels will need to be tested and re-pressurised? The plumber didn't mention anything about this, but I will follow it up once I understand.

 

[chris watkins]

Hi Ian
yes, both need to be check & adjusted to suit the pump they can both act as storage &/or expansion vessels (or not is they are flat). The pump should not be starting on any small amount of water usage.
Would be unusual for cylinder to leak but not uncommon for vessels to leak, you do not sound to impressed be the plumber?? this is a specialist area, why not try for a booster pump / un-vented specialist.

 

[IanCun]

The first plumber didn't seem to know what the components were (and told me the pump was for recirculation), but the guy that just came out was very helpful and spotted the possible leak - but didn't mention anything about re-pressurising the vessels, so I wanted to double check here, as replacing the whole cylinder would be expensive and you guys have been a huge help.

I'd love to get a repair quote from a specialist in the booster-pump/un-vented area, but I can't find one - I tried to make a post on these forums in the "I'm looking for a Plumber or Gas engineer" section, but it hasn't appeared for some reason.

Do you have any advice on how I could find a specialist near Altrincham/Sale (South Manchester), I've done googling but can't find anything.

 

[IanCun]

Sorry for all the questions, but I was also wondering why I actually need a booster pump if I've got a pressurised unvented system - as I thought that this means that the hot water pressure should be the same as the cold? Our cold water pressure seems fine - but if I turn the booster pump off then the hot water pressure is terrible (a trickle), whereas the cold water pressure is fine.

 

[chris watkins]

Just as an update... I tried turning the pump off, but it really reduced the water pressure on the taps (so low that a shower would be a no-go).

It sounds like the incoming main (flow rate) is not enough to supply all your plumbing system.

 

[chris watkins]

oop's sorry, should read your post properly, it does sound like it has been piped up in a strainge way but would need to have a look to check why ??

 

[GrahamM]

Looks a strange one alright.
Any chance can get idea of where the inlet and outlet pipes to pump are going?

Does the plumber have his Unvented qualification? If not he should not really be working on anything related to the cylinder although a decent plumber should know his way about.

 

[IanCun]

Yeah it has me really confused and it sounds like there's a problem somewhere in the system, but it's been hard for the guys that have seen it so far to diagnose. As soon as I use any hot water tap, it starts up the booster pump which seems strange. I can understand it may be needed for multiple showers, but if I just use a sink hot tap for a couple of seconds the booster kicks in (but never for cold water).

I'm going to try a company called easyflow.co.uk as they seem to do unvented services, but I'll call first to see if they are also familiar with booster pumps. I want to get it sorted soon, as the possible leak in the cylinder has me worried - we've just moved in and are about to start decorading, so I'm dreading anything going wrong. The noisy pump was bad enough, but now it seems like there's more to it.

Looks a strange one alright.
Any chance can get idea of where the inlet and outlet pipes to pump are going?

Does the plumber have his Unvented qualification? If not he should not really be working on anything related to the cylinder although a decent plumber should know his way about.

Would it help if I took some better photos of the booster pump/garage pipe system and the one in the airing cupboard? I can try and match up the pipes in the photos and see if that helps what goes where.

 

[chris watkins]

Can you trace the incoming cold mains pipework Ian ? It would normally come in from the street mains & go to a storage tank either basement or loft then out & down to booster pump through pump & then on to the pipe work next to the cylinder. Coming up from floor level to under the big red expansion vessel over & back down a to the big brass pressure reducing valve, straight on down goes to the cold feed into the hot water cylinder the pipe coming out to the right hand side of the pressure reducing valve is the balanced cold (with red handled gate valve) then it splits one going up & one down to feed the cold water taps with balanced pressure cold water. Can not see any of the hot water pipe work can you race / photo this does it go through the pump ?? the first guy said it did ????

 

[IanCun]

Can you trace the incoming cold mains pipework Ian ? It would normally come in from the street mains & go to a storage tank either basement or loft then out & down to booster pump through pump & then on to the pipe work next to the cylinder. Coming up from floor level to under the big red expansion vessel over & back down a to the big brass pressure reducing valve, straight on down goes to the cold feed into the hot water cylinder the pipe coming out to the right hand side of the pressure reducing valve is the balanced cold (with red handled gate valve) then it splits one going up & one down to feed the cold water taps with balanced pressure cold water. Can not see any of the hot water pipe work can you race / photo this does it go through the pump ?? the first guy said it did ????

I'll try and get some more photos today or tomorrow and trace the pipework through to get a layout 🙂