shower pump eraticly on and off - kind of!

[minmax89]

Hi all!

I've been plumbing (domestic) on and off for about 5 years now so I've a lot still to learn. I was called out to a woman's house the other day with a problem I'm not sure I can fix. As with most things, I'll be fully confident I can fix it once I get it diagnosed...

So, She has two bathrooms on first floor with hot cylinder and 3-bar positive head Stewart Turner pump, which feeds two showers, hot taps at the basins and the kitchen sink down stairs.
The problem is in the main bathroom - when you open the shower mixer (half and half mix of hot and cold) the pump doesn't kick in. If you open the shower valve with the lever all the way over to cold, pump kicks in and you can adjust the temp and it runs fine. What the owner was doing was running the basin hot tap to get the pump going. So it seems like an air lock in the hot side right?
I had a look at the pipework in the airing cupboard and it seems ok. There is a Warix flange on the hot cylinder feeding the hot side of the pump.
I went into the loft - the cold water tank is about 2ft raised off the loft floor. The pipework coming off it is a MESS! There's enough brass elbows and tee's to sink a ship and nearly all the pipework within looks to have been installed when the bathrooms were done about 7 years ago. So the owner says anyway.

So I say, "how longs this been happening?"
"Oh a year or so I think."
"So, not since it was installed then?"
"No. I don't think so..."

Can anyone point me in the right direction of how to start diagnosing this?

I thought that if it was an airlock, the pump would drive it out and that would be the end of that.

I think the pipework might be the issue but don't want to start working on it till I'm pretty sure.

A Million thanks in advance for any help. I could walk away and tell her to get a s**t hot plumber in but I want to know what's wrong and feel I could learn a lot in the process.

Adam

 

[gassafe]

If its all piped up correctly check the filters on the pump 1st, could be a nice easy fix.

 

[rpm]

I was thinking it could be the ST pump if thats 7yrs old but if the other shower is on the same floor and ok then that rules that out.

 

[minmax89]

Gosh, I feel a bit stupid not thinking of the filters. AND when you open the shower on solely the hot side there is barely a drip and I would of thought there would be some amount of water from what is essentially a gravity fed shower head with a head pressure of like 1.5-2m.



I forgot to mention, there is another problem!

The hot tap in kitchen. when you turn it on, you can hear the pump kicking in upstairs but after about 30 seconds it goes off for like 20 seconds. then back on again, and so on... If you then try mixing the cold side (mains) into the tap it completely knocks any hot out of it and the pump goes off straight away and wont come on at all until you shut off the cold side completely. Is this possibly a separate issue though??
Sorry forgot to mention this in original post.

 

[gassafe]

Sounds like the pump is being starved of water... The kitchen tap sounds like a back flow problem, may need a check valve on the hot or a new tap that mixes at the spout & not the tap body.

 

[minmax89]

Well I went back to try something with this and I think I've made it worse!!!

There was evidence of a leak at the pump area. The flexy hot inlet was corroded, floor was damp and ceiling below has staining. Hot inlet flexy was corroded so removed it and found the rubber/mesh filter had disintegrated and what was left of the mesh was stuck a little further up the pipe.






The pipework between flange and pump had an elbow so changed it for copper with bends. This is what I ended up with:




Thought that might of fixed the problem but it's made it worse!! the bathroom basin (same floor) is now doing this:
[video=youtube_share;v8IVgElTZe8]http://youtu.be/v8IVgElTZe8[/video]

What is going on??!!

the cold side of the pump runs totally fine.

the pipe work on the hot outlet side of the pump seems very complicated.
3/4" goes from pump:

then to 1" here:

goes into the loft to this:


and then it's up, down, left right dropping back down to two showers and two basins on first floor and further down to the kitchen tap.


it seems when I improved the flow to the pump by removing elbow it's made the problem worse. So, I've now really got to fix this!

I spoke to a far more experienced plumber than me on the phone and he thinks the pump might be at fault and that sticking a negative head pump in would sort it all out. I kinda need to guarantee that though (price of negative head pump). He suggested I do the following to test:
Remove hot pump inlet and run into a bucket to check flow to the pump is good. If so, reconnect and remove hot outlet pipe and run that, through the pump into a bucket and see what that does. If problem occurs, it's the pump and I should replace. Pump is about 8 year old so I'm told.
do you think that would be a definitive approach and solution??

Surely it can't be the pipework because it was all working fine for a number of years.


I just had a thought - could it be that the corrosion on the old flex hot inlet has affected the flow switch?

The intermittent nature of the issue is making this difficult for me to diagnose. I can only be certain the problem is not on the cold side.


Your help is appreciated so much so a million thanks in advance.

Adam

 

[minmax89]

There's something else of slight concern - that 3/4" push fit on the flange, although not leaking water, the pipe seemed quite loose in it? could it be enough to be sucking in air?

 

[Chalked]

Some pumps only have one flow switch, you would normally connect the hot to that side.

 

[minmax89]

Some pumps only have one flow switch, you would normally connect the hot to that side.

no, there's flow switches on both sides.

 

[Ch4 plumbing]

The pump is drawing air in from somewhere, take a look at the Surrey Flange and check it's piped up correctly.

 

[minmax89]

The pump is drawing air in from somewhere, take a look at the Surrey Flange and check it's piped up correctly.

Thanks. The pump is fed by the side outlet. vertical is just going up and venting over cold water storage tank. Is there ever a surrey flange with oulets opposite to the pic below:

If not, then no, it seems to be piped correctly.

Can/Do these Surrey flanges ever fail internally so that the supposed 'air free' outlet is compromised and thus sucks in air?

 

[Ch4 plumbing]

Is it defiantly that particular make? I fit the Warix Flange type and the shower feed comes off the top and the vent/hot water down service comes off the side?

 

[gassafe]

Looks like a mess... Really old system too, that thank will want ripping out soon.

i would recommend unvented cylinder as its cheaper than a negative pump plus new cylinder in the future... Or stick a salamander whole house pump in that is suitable for the basins etc...

 

[minmax89]

Looks like a mess... Really old system too, that thank will want ripping out soon.

i would recommend unvented cylinder as its cheaper than a negative pump plus new cylinder in the future... Or stick a salamander whole house pump in that is suitable for the basins etc...

sure is a mess. BUT it was working for a while (god knows how long and how long it's had this problem).

thing is, there is only one person living in the house so technically only one outlet is being used at a time. With all due respect I'm not sure think the size of the pump is the problem. It seems more to do with the pump being starved of water - after a while...

 

[Ch4 plumbing]

What size is the cwsc?

 

[minmax89]

What size is the cwsc?

About 1.2m long, 0.6m high, about the same wide.

 

[DrainMedic]

It seems like the Surrey flange has failed. Quite often, the spout of the s flange (the portion hanging down in the cylinder) is simply glued in place from new, they quite often fail and literally fall off into the cylinder, leaving the draw-off full of air.
You have to think logically to solve these kind of problems.
Negative head pump is ruled out totally, it worked before now, so something has failed, it's not an installation problem.
Pipework issues are ruled out too, again, it's worked for years!
If the pump is drawing air in, it'll be on the hot side (you say the cold side is fine?) and for it to draw air in, it would have to be down the vent pipe of the cylinder, it can only do this if the s flange has failed.
It's certainly worth leaving everything exactly as it is and just remove the outlet pipe work from the pump. Connect some plastic pipe to it and run it off into the bath. If that works fine, the problem is past the pump. I suspect it will be ok, as the other shower etc is working fine. PM me and I'll give you my number for you to give me a call when you're at the job if you like, I'll talk you through some checks you can do.

Dave

 

[minmax89]

It seems like the Surrey flange has failed. Quite often, the spout of the s flange (the portion hanging down in the cylinder) is simply glued in place from new, they quite often fail and literally fall off into the cylinder, leaving the draw-off full of air.
You have to think logically to solve these kind of problems.
Negative head pump is ruled out totally, it worked before now, so something has failed, it's not an installation problem.
Pipework issues are ruled out too, again, it's worked for years!
If the pump is drawing air in, it'll be on the hot side (you say the cold side is fine?) and for it to draw air in, it would have to be down the vent pipe of the cylinder, it can only do this if the s flange has failed.
It's certainly worth leaving everything exactly as it is and just remove the outlet pipe work from the pump. Connect some plastic pipe to it and run it off into the bath. If that works fine, the problem is past the pump. I suspect it will be ok, as the other shower etc is working fine. PM me and I'll give you my number for you to give me a call when you're at the job if you like, I'll talk you through some checks you can do.

Dave

Thanks soooo much Dave. Sending you a PM now...

 

[minmax89]

Just want to say a massive thanks to Dave AKA Drain Medic. His encouragement and advice was outstanding today and because of that, I not only fixed this problem but more importantly, diagnosed the problem properly in the first place.

Just to finish of this thread I'll summarise what I did.

The Problem was the shower pump was behaving erratically with all outlets it was supplying. Running for 20 odd seconds then switching off, back on, off, etc.

1st - removed hot outlet from pump. connected hose to it and run into bath. Problem still there so it wasn't the pipework after the pump.

2nd - knowing that the cold side of the pump was running fine, took off all four connections to the pump. put the cold pipes into the hot side of the pump and ran the cold. Pump kicked in and ran fine. So, nothing wrong with the pump (As in flow switch, impeller, etc.).

3rd - To check the gravity flow of the hot water to the pump. connected up a hose to the hot outlet of the S-flange and ran into the bath. not great flow to be honest. there was about 3m of head pressure, 28mm pipe from CWS tanks to hot cylinder. But flow was poor. no doubt about that.

So all connected up the last test I did (thanks Dave!) was to cap off the vent pipe. Hey PRESTO!!! Problem gone!

So that means the pump was sucking in air from the vent pipe due to a restriction in the hot cylinder. Somewhere!


Very happy indeed and mega thanks again Dave.

Cheers
Adam

 

[DrainMedic]

You'll have me in tears Adam!

The series of tests we ran through over the phone may have seemed daft, but each is designed to eliminate a certain part of the system. The final test (temporarily capping the vent pipe) proved that the pump was drawing in air down that pipe, and the only reason it would ever do that is if there's a restriction in the cylinder feed pipework.
Replacing the pipework to the cylinder (or clearing it, whichever you choose) is a pretty simple solution to a thorn in your side!

Glad you managed to sort it anyway, and if you get stuck again, you have my number.

 

[Ch4 plumbing]

You'll have me in tears Adam!

The series of tests we ran through over the phone may have seemed daft, but each is designed to eliminate a certain part of the system. The final test (temporarily capping the vent pipe) proved that the pump was drawing in air down that pipe, and the only reason it would ever do that is if there's a restriction in the cylinder feed pipework.
Replacing the pipework to the cylinder (or clearing it, whichever you choose) is a pretty simple solution to a thorn in your side!

Glad you managed to sort it anyway, and if you get stuck again, you have my number.

Well ill done mate, brilliant result.

 

[Dotty]

Gladdens the heart to see newbies helping newbies. ...

 

[gassafe]

So all connected up the last test I did (thanks Dave!) was to cap off the vent pipe. Hey PRESTO!!! Problem gone!

So that means the pump was sucking in air from the vent pipe due to a restriction in the hot cylinder. Somewhere!


Very happy indeed and mega thanks again Dave.

Cheers
Adam

its good to see your close to finding the fault, from reading the post it sounded like you left the vent capped lol!