Negative Head pump not doing the business

BenEadir

Hi all,

Here's the story: House was renovated a few years ago. We live in an area with low water pressure. The hot water system had a regular (positive head?) pump installed to power the two upstairs showers and the downstairs bath/shower and it provided a really strong powerful jet of water. I don't know anything about plumbing but this is a summary of our system:-

- Two water tanks in the attic
- New hot water tank (when renovated 4 years ago) in the hot press which is beside one of the bathrooms upstairs.
- Two showers upstairs and one shower/bath downstairs.

One of the upstairs showers (the 'spare/guest' shower which is only used once or twice a week) was always a bit finiky. Sometimes when turned on it would fire up grand but sometimes you'd have to drop the shower head to the base of the shower and shake it to kick start the flow and when that didn't work we discovered that running the hot tap on the bath/shower downstairs would do the trick but only after it had cleared what I assume to be some sort of airlock i.e. it would start slowly, splutter a good bit, build up pressure, splutter some more and eventually get to full flow. this process seemed to kick start things and the upstairs shower would start to flow.

Over the last few months we've had a family member staying to attend college so the affected shower is being used daily and the problem was occurring every single morning needing someone to run the downstairs bath hot tap to get it going but the main shower upstairs always worked perfectly until a few weeks ago when it too acquired the same problem i.e. it wouldn't fire up unless you dropped the shower head and shook it and if that didn't work you'd have to run the downstairs bath hot tap.

I got the plumber who installed the system when the house was renovated back in and he recommended that the existing pump with a negative head pump as there isn't enough natural pressure in the hot water system to start the flow. He's the expert so I went with his advice. the pumps was installed and now things are worse!! Not only does the downstairs bath hot tap have to be run to kick start either shower upstairs but the power from this pump compared to the previous pump is rubbish. It's really weak in comparison.

I don't undertand how a positive head pump was specified 4 years ago and did a pretty good job most of the time and now, with no changes to our plumbing or house layout and no additional showers or anything added, a negative head pump is required. I kind of understand why it may have been an error installing the positive head pump in the first place if the plumber thought there would be enough pressure in the system but it turned out there wasn't but what I don't understand is why installing a negative head pump has actually made things worse!!

I really don't know how to discuss this with my plumber and I'm hoping that some fellow Boardsie here will a) help me understand what might be going on with my how water system and b) give me a few things to say to my plumber or a few questions to ask him???

FYI here are the labels from the newly installed negative head pump which is installed on the ground of the hot press beside the hot water tank.





Appreciate any feedback you guys can give me whatsoever and apologies for the long post.

Ben

corkgsxr

Take a picture of the hot press.

oikster

Upstairs shower filters,have they been checked?

BenEadir

oikster wrote: »

Upstairs shower filters,have they been checked?

I've no idea. I assume (very stupid thing to do I know) that the plumber would have checked basic things like that (I didn't know showers had filters!!) before jumping to the conclusion that an expensive new negative head pump was required :eek:

Where would I find the shower filters? Is is something I could/should have been checking myself? I have a reasonable size aquarium so I'm familiar with the concept of cleaning filters.

Here's some pictures of the hotpress





Ben

oikster

Without having seen the shower in question, this will only be supposition but the filters are normally located right at the inlets.Another explanation could be a recurring air lock.Because the flow switches at the pump rely on movement of liquid to actuate, an airlock or blockage would be my best guess.

BenEadir

oikster wrote: »

Without having seen the shower in question, this will only be supposition but the filters are normally located right at the inlets.Another explanation could be a recurring air lock.Because the flow switches at the pump rely on movement of liquid to actuate, an airlock or blockage would be my best guess.

Thanks Oikster, really appreciate the input. My amateur instinct is also telling me it's an airlock related issue as running the downstairs bath hot tap, which starts off with just a drizzle and after a minute of spluttering eventually gets a flow going, does kick start the pump which I guess in turn is what gets the upstairs showers going.

My main concerns are:-

1. If the problem was indeed an airlock issue all along (same procedure was needed to get the old positive head pump going) why would the plumber go ahead and install a new negative head pump?

2. How are airlock issues generally diagnosed and addressed?

3. Will the negative head pump eventually deliver a powerful jet of water comparable with the old positive head pump once the air lock issue has been resolved? Are negative head pumps weaker than positive head pumps?

Ben

oikster

Because a negative head pump is, ironically, sitting in a positive state when not in use it can sometimes be,believe it or not, the least disruptive solution to a difficult to solve airlock. In your case it seems that there isn't even enough movement to drop the pressure at the pump to bring it on. More in-depth investigation needed I'm afraid.

BenEadir

oikster wrote: »

Because a negative head pump is, ironically, sitting in a positive state when not in use it can sometimes be,believe it or not, the least disruptive solution to a difficult to solve airlock. In your case it seems that there isn't even enough movement to drop the pressure at the pump to bring it on. More in-depth investigation needed I'm afraid.

Thanks Oikster, I do like a good puzzle but this one is getting the better of me

Any thoughts on why the new pumps produces such a weak flow compared to the old pump? I assume (there's that dangerous word again) that once the pump is started (whether normally or via the kick start process we are currently having to use) it works normally i.e. it's output isn't restricted in any way?

The other issue I can't understand is why, in a fixed system which hasn't been changed in any way, the pressure goes from being sufficient to start a positive head pump when it was installed 4 years ago to being insufficient now? Are the physics (getting way out of my depth here now) not constant i.e. the hot water tank is in exactly the same location as are the showers etc. What could have changed to reduce the natural pressure to the extent it won't fire up any sort of pump?

Confused.com here

Ben

oikster

I'm afraid we are back to partial blockage of the pipework which can be a real challenge to locate and sort.But I would start with the basic stuff pump and shower filters. As a matter of interest do you know where the supply from your hot water cylinder to your pump is taken from. By this I mean from what part of the cylinder. It can be from the pipe coming from the very top of the cylinder or taken from the side of the cylinder about 6 to 8 inches down.Also is there a mixing valve on this line as these also have filters.

BenEadir

oikster wrote: »

As a matter of interest do you know where the supply from your hot water cylinder to your pump is taken from. By this I mean from what part of the cylinder. It can be from the pipe coming from the very top of the cylinder or taken from the side of the cylinder about 6 to 8 inches down.

I personally don't know. Here's the top of the cylinder, it has some pipes coming out of it



and here's a picture of the side of the cylinder where there is another pipe coming out about 8-10 inches down from the top of the cylinder. I guess this could be the pipe supplying the pump?

oikster wrote: »

Also is there a mixing valve on this line as these also have filters.

I've no idea I'm afraid

Ben

esox28

Its one of three things or all three, after you've checked the filters.

Reed switch faulty

PCB fautly

flow indicating float getting stuck.

Reed switches and PCB come as a package for around €70 afaik for the 2.0 bar monsoon. Either way you will need to get a compendent plumber or a service call for shower manufacturers.

BenEadir

esox28 wrote: »

Reed switches and PCB come as a package for around €70 afaik for the 2.0 bar monsoon.

The 2.0 bar monsoon is literally brand new (a week old) and the problem existed (not as bad actually!!) before the old (still relatively new) pump was replaced so I'm guessing it can't be a failure in the pump.

I probably should have mentioned it before but one thing which could be significant is the fact that when the problem is 'fixed' by running the downstairs bath hot tap until all the air splutters have cleared the showers will then work fine during the day i.e. not only do they start to work immediately but if someone uses the shower that afternoon or evening the pump starts off fine. It isn't until the following morning again when the problem re-occurs. I guess whatever the problem is it takes +/- 24 hours to build up again to the point where it requires the downstairs bath hot tap to be run to clear it again.

What I'm still interested in knowing is why the power from this new pump, once it is engaged, is so much weaker than the previous positive head pump? I think the previous pump was also 2.0 bar but the power felt twice or three times as much. Are negative head pumps always weaker than their positive head equivalents or does that just demonstrate how little I actually know about this subject???

Ben

esox28

if its new just get a warrenty call out from service eng, just to rule out the the problem isent with the pump itself, form what you are saying it also could be the pressure vessel which has deflated and should have been checked by installer on commissioning the pump into operation.

BenEadir

esox28 wrote: »

if its new just get a warrenty call out from service eng, just to rule out the the problem isent with the pump itself, form what you are saying it also could be the pressure vessel which has deflated and should have been checked by installer on commissioning the pump into operation.

Thanks esox28, I'll suggest a warranty call out to my plumber.

Can you tell me where the pressure vessel is likely to be located?

Ben

oikster

Yes your supply is taken from the top of the cylinder and is protected from air ingress by the fitting used. I am now back to the airlock problem and all I can suggest is that you get your plumber back to see if he can locate the reason for this recurring.

BenEadir

oikster wrote: »

Yes your supply is taken from the top of the cylinder and is protected from air ingress by the fitting used. I am now back to the airlock problem and all I can suggest is that you get your plumber back to see if he can locate the reason for this recurring.

Cheers oikster. Enough of this problem. Time to watch Arsenal give United a good old fashioned spanking

I hope neither yourself nor esox28 are united fans :eek:

Ben

esox28

arsenal left it all in europe nothing left, rvp will step up 1 nill united:D

oikster

Of course I'm a united fan...........................LEEDS UNITED:D:D:D

BenEadir

esox28 wrote: »

arsenal left it all in europe nothing left, rvp will step up 1 nill united:D

Your crystal ball is working quite well so far Esox!!

Ben

esox28

One nill one nill onnne nillll.

BenEadir

esox28 wrote: »

One nill one nill onnne nillll.

Well done Esox. My LFC heart always wants to see United lose but my head says its a great result for us. It reels Arsenal in a bit and keeps you lads out of the top four :-) A six point weekend for us!

Ben

oikster

One more thing Ben, I wonder were the hoses changed when the pump was changed or are they the originals?

BenEadir

oikster wrote: »

One more thing Ben, I wonder were the hoses changed when the pump was changed or are they the originals?

Yes, I think they were.

FYI there is a warranty call into the pump supplier just to rule out there is an issue with the pump.

Regards,

Ben

oikster

Just a thought but I heard a story today of a similar problem with the same pump and after FOUR pump changes under warranty the problem persists.The only thing common to any other instances of this,that I have heard of,was the hoses not being changed. Possibility of air intake on the suction hose.

LIFFY FISHING

There has Never been four Monsoon pumps replaced under warantee in Ireland ever,as it would never need to be, so thats an urban myth, to confirm the pump is in working order, turn off the water & power to and from the pump, connnect the outlets to two lenghts of qualplex and into an outlet like your bath or shower, and then turn everything on, if the pump pumps and my bet isit will, ur issue is with the plumbing, & 90%of times it iz .

oikster

No urban myth LF. These pumps were supplied by Monsoon and I was talking to the man that supplied them and the man that fitted them. You may be right about the Ireland bit but that is all.

LIFFY FISHING

oikster wrote: »

No urban myth LF. These pumps were supplied by Monsoon and I was talking to the man that supplied them and the man that fitted them. You may be right about the Ireland bit but that is all.

Rubbish.

If there is a problem with a Monsoon pump its repaired not replaced, & 4 would never be replaced.

oikster

I never said that there was a problem with the pumps. I merely told you what I was told. I have seen this problem before and I know that it is not the pump.You do not know the circumstances of the job I was quoting and it was quoted as proof as to the stupidity of some so called suppliers and so called plumbers.

xstevex

Sorry for piggybacking on your thread, forgive me I'm new here and I have been following this closely.

Did you sort this problem? I ask because I'm experiencing something similar.

I'm living in an attic bedsit and all taps, shower and cistern apart from the cold in the kitchen are served by a pump located on the floor below.

The cold in the kitchen always has excellent pressure.

Now to the pump.....

The pump for starters only works sometimes ie. its working now with excellent pressure to all outlets however when I turn it the power off from the switch in the flat there is a good chance it wont turn back on when switched back on. In fact oftentimes when I stop running the water through the taps/shower or when the cistern fills and the pump stops pumping it stops working regardless of whether its switched on or not, as if it decided it's work was done.

Yesterday it didn't work at all and when I turned it on I could hear a hum emanating from the pump downstairs but alas no water came.

So in short....

The pump works intermittently.
When it works, the pressure is smashing.
When it doesn't work it hums.
When the power switch is left on when it is working it stops working when i stop running water so when i turn a tap nothing happens.
When not working there is zero flow (negative head?).
The shower head, bathroom sink etc are above all water sources.

Probably unrelated or purely coincidental/imaginary, but it seemed to work perfectly until a lad was round to sort out central heating problems.

I'm confused because it works really well when it works and before I replace it I'd like to discuss it.

Forgive me if reading the above was a pain in the arse.
Any advice would be greatly appreciated.

Thanks and all the best,

Stephen

BenEadir

Hi Stephen,

Not sure my experience will be much help.

The original plumber who did all the pipework and fitted the original positive head pump returned and fitted the negative head pump referred to above as he expected that would solve the problem. When it didn't he called out an engineer to service the (brand new) pump. It was fully tested and no fault found.

The problem remains exactly as it was before the negative head pump was installed. The only change is that now once the pump has been kick started by running the downstairs bath hot tap the pressure to the showers is less than half what it was with the original positive head pump fitted.

The other slight difference (to be pedantic) I've noticed with the negative head pump is that when the first shower of the morning is turned on it runs very weakly for about 3-5 seconds, then the flow stops all together and then you have to go downstairs to run the bath hot tap which now starts with a weaker initial flow than before, takes longer to splutter to life (about a minute) and when it eventually reaches its full flow it's only about half the power it was previously with the positive head pump in place.

There's been a lot of scratching of heads going on by my plumber. He fitted everything originally and there's been no amendments to his original pipework so he's proper confused.com. He keeps says "but it shouldn't be doing that" or "a negative head pump should clear that problem".

Next up is a larger negative head pump apparently. That will probably be fitted early next week.

If it fixes the problem I'll report back. Until then the morning process of air lock freeing will continue I'm afraid :rolleyes:

Ben

xstevex

Cheers Ben, plenty of head scratching going on here too. Pain in the goolies but I'm sure we'll get there in the end.

Thanks again.

K.Flyer

Hi xstevex,
A couple of questions...
What make of pump are you using?
What is the linear height from the shower pump to the shower head?
Is the affected bathroom directly above the pump or some distance away. e.g. one floor up and ten feet across..
Thanks.
K.F.

xstevex

Hi K.F.

Thanks for taking the time to reply.

I dont have access to the flat below where the pump is so cant take a picture at the moment. The landlord informs me that the pump is a Stuart Turner (I will definitely confirm this tomorrow).

The bathroom is located directly above the pump , the sink in the kitchen where the hot tap also uses the pump is about 10 foot from shower.

So the shower head (which is on a flex) when sitting in the wall fitting is approx 15/16 feet from pump (10 feet when lying in the shower tray).

Don't know if this info helps but thanks all the same.

From previous posts I noticed people were searching for leaks, there are no leaks as far as I am aware. When the pump is working the shower drips heavily when not in use.

I also noticed a couple of others have turned the turbines in the pump with screwdrivers or biros and they all of a sudden started working. Another chap gave the pump a few solid smacks on the floor and hasn't looked back.

Have a good night, cheers.

S

ps. its not working again just humming when I hit the power button.

K.Flyer

xstevex wrote: »

... its not working again just humming when I hit the power button.

If the capacitor is gone the motor will humm for approx 30 seconds to a minute and then stop, start by changing the capacitor.
Another problem I have come across can be one of the impellers jammed by debris or a dislodged strainer on the intake side of the pump, this will also cause the pump to humm for a short while and then stop.
These are two things which I would have checked first before doing anything else.

xstevex

Cheers K.

Yeah I'll check those things tomorrow when I can get at the pump.

Turned it on to check the hum just now and of course the pump worked perfectly, high pressure water flowing like a dream.

cerastes

OP
Is there likely to be some restriction of the water supply side of things? if there are non return valves in these, I assume they cant be fitted incorrectly?
or that it just wouldnt work if they were?

Or is it possible that some part of the layout/routing of the piping isnt or was never conducive to letting the flow getting going enough to bring the pump in?
Like the inverted U at the outlet of the pump prior to the valves?

edit)Or the taps and outlets, do you know what they are rated to operate at? low or high pressure, ie were they sourced in Ireland or through a company that obtains products from the UK?
edit) the flange at the top of the tank, I just did some googling, could it be faulty or incorrectly installed? allowing air bubbles in? seems they have a form of a stack pointing down into the tank where it would be unhindered by air bubbles?
edit) any braided hoses twisted or damaged, shower hoses restricted somehow or the heads needing cleaning?
Ive also come across a mention of gate valves as isolation being restricing to flow comapred to ball valve type isolation??

Just throwing ideas out there, not overly familiar with negative head pumps, but interested.
Ive wondered if it its possible to replace a negative head pump give their cost with a positive head and some kind of pressure vessel you could fit in the supply lines cheaper, but Ive no idea if this would work.

BenEadir

Hi guys,

Larger capacity negative head pump fitted today. Not sure what it is.

I'm off on a business trip tomorrow for 10 days so when I get back I'll either have a pissed off Missus because the problem is still there which adds to the challenge of getting kids out to school in the morning or I'll be welcomed back with open arms as the showers are back working properly again.

I personally suspect the idea of a larger pump is akin to the DIY'er using a larger hammer i.e. doesn't matter what the actual problem is, fit a huge pump and the force of the pump will over ride the root cause of the problem.

I do appreciate all the suggestions.

When I get back I'll take some measurements and photo's etc to answer some of the questions above.

Cheers,

Ben

K.Flyer

cerastes wrote: »

.....Ive wondered if it its possible to replace a negative head pump give their cost with a positive head and some kind of pressure vessel you could fit in the supply lines cheaper, but Ive no idea if this would work.

The pressure vessel is one of the key parts of a negative head pump, but another important part is the low pressure switch.
In order to fit the low pressure switch you would need to have a way of fitting it into the pipework and connected into the pump electrics which would involve changing the pcb from a positive type to a negative type. All in all not worth the trouble and cost of trying, but I get where your coming from.

K.Flyer

oikster wrote: »

Yes your supply is taken from the top of the cylinder and is protected from air ingress by the fitting used. I am now back to the airlock problem and all I can suggest is that you get your plumber back to see if he can locate the reason for this recurring.

Could he have plumbed off the Warix the wrong way. Most Warix flanges you take the top connection to the pump and the lower connection to other services and vent. If he has, there may be trapped air at the top of the flange or air bubbles could be getting into the pump causing it not to run correctly.

oikster

K.Flyer wrote: »

Could he have plumbed off the Warix the wrong way. Most Warix flanges you take the top connection to the pump and the lower connection to other services and vent. If he has, there may be trapped air at the top of the flange or air bubbles could be getting into the pump causing it not to run correctly.

You may be on to something there K F as the picture on page one shows the pump being fed from the lower outlet.I am convinced that this is an air problem but I was damned if I could see where it was coming from. By the way, I always use Essex flanges myself.

oikster

I had a look at a Salamander (surrey flange) which is almost identical to the one used here but the vent is definitely taken from the top connection. So if it is one of these used here then it is connected correctly.

K.Flyer

oikster wrote: »

I had a look at a Salamander (surrey flange) which is almost identical to the one used here but the vent is definitely taken from the top connection. So if it is one of these used here then it is connected correctly.

I was only looking at one today and saw the same thing, but you beat me to the post. Still worth mentioning to the installer to double check it.
From my exp. once the supply pipes are free of air, the pump will drive any air out of the rest of system.
It's the sort of problem you could probably find and fix in a short while on site, but a bit difficult without seeing it.
I would be pulling the outlet connections off first and running the pump checking for full flow, if thats ok, it has to be plumbing or shower valve issues.

oikster

K.Flyer wrote: »

I was only looking at one today and saw the same thing, but you beat me to the post. Still worth mentioning to the installer to double check it.
From my exp. once the supply pipes are free of air, the pump will drive any air out of the rest of system.
It's the sort of problem you could probably find and fix in a short while on site, but a bit difficult without seeing it.
I would be pulling the outlet connections off first and running the pump checking for full flow, if thats ok, it has to be plumbing or shower valve issues.

I have come across this problem twice,three times if you include this one.Neither of the other two were my own installs. One I have already mentioned on this thread and has still not been resolved but I have the supplier primed to keep me posted. The other instance was at the request of a mate, a favour for a favour sort of thing.Same symptoms and believe me we checked everything. Even went as far as cleaning out the storage tanks and pipework and to this day the owner has to release air from the pump about once a month.As I have said I have never experienced this problem on my own installs but I always use Essex flanges. Could it be related?

fredgalway

Hi BenThere Had same problem. I have sent you a pm, if you contact me I will try to help.