Use mains water throughout the house

8Choc · 19-05-2017 07:30PM #1

Hi, I was thinking of putting a tee connector on the mains feed to my attic tank and connecting to another tee on the output from the tank , and also putting a one way valve between the new tee on the output and the tank itself ( to stop the tank filling from the output) , has anybody ever done this ?, or know why it wouldn't work ? .I am trying to increase pressure in the house specifically the upstairs shower . As a test I fed the garden hose ( main fed ) through the upstairs bathroom window and experimented by filling a litre plastic bottle with the shower ( head off ) and then the garden hose and the hose filled it twice as fast !. Would anyone with experience know why I couldn't do this ?. Thanks in advance

K.Flyer · 19-05-2017 07:38PM

8Choc wrote: »

Hi, I was thinking of putting a tee connector on the mains feed to my attic tank and connecting to another tee on the output from the tank , and also putting a one way valve between the new tee on the output and the tank itself ( to stop the tank filling from the output) , has anybody ever done this ?, or know why it wouldn't work ? .I am trying to increase pressure in the house specifically the upstairs shower . As a test I fed the garden hose ( main fed ) through the upstairs bathroom window and experimented by filling a litre plastic bottle with the shower ( head off ) and then the garden hose and the hose filled it twice as fast !. Would anyone with experience know why I couldn't do this ?. Thanks in advance

You cannot do what you are thinking of without it ending in tears and a very wet house.

What type of shower is it?
Usually the cheapest way to boost your water pressure, especially for a shower, is by installing a water pump or a pumped unit like a Triton AS-2000.

8Choc · 19-05-2017 07:44PM

Thanks for reply - Why Tears ? Its a new gravity fed shower , works quite well but could do with a boost. Pumps etc. cost money , the pressure in the incoming mains is free etc.etc....

K.Flyer · 19-05-2017 07:46PM

8Choc wrote: »

Thanks for reply - Why Tears ? Its a new gravity fed shower , works quite well but could do with a boost. Pumps etc. cost money , the pressure in the incoming mains is free etc.etc....

Your going to boost the cold water, what about the hot water??

8Choc · 19-05-2017 07:51PM

Your right K.Flyer , there are separate feeds for hot and cold from the tank, so I just tee into both ?

my3cents · 19-05-2017 08:02PM

The downside to your plan OP is that you will increase the noise from water flowing in the pipes when you use any of the cold taps and flush the toilet. I know because my parents house is plumbed that way, flush a toilet and you wake the dead.

Another problem is at times of low demand on the water main late at night the pressure can go well above what it is during the day. Your header tank evens that all out.

A gravity fed shower is low pressure so how will it perform with varying mains pressure?

K.Flyer · 19-05-2017 08:10PM

8Choc wrote: »

Your right K.Flyer , there are separate feeds for hot and cold from the tank, so I just tee into both ?

Nope, this is where the trouble can start.
If you have a standard domestic hot water cylinder you will most likely cause it to leak as they are not designed to take high pressure mains water.
The mains water will just push back up through the open vent pipe overhanging the tank, if you blank it off, which is what I have seen done, then the pressure builds up in the cylinder, add some heat for hot water and kersplash.
I understand your thinking, but honestly its a bad idea.
You could change the cylinder for an unvented type, but it would be cheaper to fit a pump.

Mech1 · 19-05-2017 08:17PM

Also if for any reason the mains water goes off your stagnant and possibly dirty infected water system might siphon back into our treated clean water supply.

8Choc · 19-05-2017 08:19PM

Thanks - don't get the noise thing , don't understand how it would be different ? Toilet cistern would just fill quicker ? . With regards to the pressure, I checked it there earlier 6pm on a friday ( busy time , people heading out etc.etc. ) and pressure was really good . I was wrong do to say I'd use a oneway valve to stop the tank from filling from the output cause that would never open even if mains water was switched off, probably should use a pressure valve of some type (takes feed from highest pressure , i.e. if mains went off it would switch back to tank ) or even a manual valve ( if mains went off you could turn it open and have have the 100 litres in the tank available etc..) or even get rid of the tank altogether ( how often does the water go off these days ??? )

K.Flyer · 19-05-2017 08:33PM

Did you not read my post in relation to the Hot Water Cylinder, standard household cylinders are not designed to be sealed or be subjected to mains water pressure.

my3cents · 19-05-2017 08:54PM

K.Flyer wrote: »

Did you not read my post in relation to the Hot Water Cylinder, standard household cylinders are not designed to be sealed or be subjected to mains water pressure.

I can remember a neighbor connecting a std HWC directly to the mains and the interesting thing was is lasted a few days before it opened up down the side seam.

Lu Tze · 19-05-2017 09:04PM

Interesting idea, possibly the inclusion of a pressure reducing valve limiting the the pressure might relieve the the hot water tank issues. Could be 60-80m of head in the water main, reducing to 10-12m would still double the pressure in the house water system. Pretty disastrous if it goes wrong though

K.Flyer · 19-05-2017 09:15PM

Lu Tze wrote: »

Interesting idea, possibly the inclusion of a pressure reducing valve limiting the the pressure might relieve the the hot water tank issues. Could be 60-80m of head in the water main, reducing to 10-12m would still double the pressure in the house water system. Pretty disastrous if it goes wrong though

What about the water flowing back up through the open vent pipe from the cylinder and pitching back into the attic tank causing it to overfill?

Lu Tze · 19-05-2017 09:27PM

K.Flyer wrote: »

What about the water flowing back up through the open vent pipe from the cylinder and pitching back into the attic tank causing it to overfill?

Fair enough, while water system design is something I do, I'm not ofay with household plumbing systems. Was just suggesting a solution for reducing the excessive mains pressure to something more reasonable, but still in excess of the head available from the attic tank.

8Choc · 19-05-2017 09:29PM

Thanks K.Flyer , I knew i was missing something, the hot water tank vent pipe , thought I was a genius there for a minute........... Maybe a pressure relief valve on the vent pipe ? , Mains pressure at that height cant be enough to breach a cylinder. etc ...???.

K.Flyer · 19-05-2017 09:31PM

The correct equipment is available and it's becoming increasingly common to find on new and retro installations complete with the appropriate safety devices to minimise or prevent property damage and personal harm.
But attempting what the O.P. is suuggesting is a recipe for disaster.

Dtp1979 · 19-05-2017 09:32PM

Lu Tze wrote: »

Interesting idea, possibly the inclusion of a pressure reducing valve limiting the the pressure might relieve the the hot water tank issues. Could be 60-80m of head in the water main, reducing to 10-12m would still double the pressure in the house water system. Pretty disastrous if it goes wrong though

No no no. God read k flyers post. If you blank off the vent and pressurise the plumbing then it needs to expand to say the least. There's no way around any of this without flooding a house. Install a booster pump op if you want better pressure

K.Flyer · 19-05-2017 09:36PM

8Choc wrote: »

Thanks K.Flyer , I knew i was missing something, the hot water tank vent pipe , thought I was a genius there for a minute........... Maybe a pressure relief valve on the vent pipe ? , Mains pressure at that height cant be enough to breach a cylinder. etc ...???.

You are asking for trouble, advise given, take it or leave it, but in a nutshell, if you do attempt it and it all goes wrong, you will have some explaining to do with your household insurance company :pac:

Dtp1979 · 19-05-2017 09:46PM

K.Flyer wrote: »

You are asking for trouble, advise given, take it or leave it, but in a nutshell, if you do attempt it and it all goes wrong, you will have some explaining to do with your household insurance company :pac:

And to the plumber who comes to fix it, and to the guy who's re slabbing your ceiling, and to the plasterer, and to the guy re laying new carpets. And to your missus. God help you

gctest50 · 19-05-2017 09:48PM

8Choc wrote: »

Thanks K.Flyer , I knew i was missing something, the hot water tank vent pipe , thought I was a genius there for a minute........... Maybe a pressure relief valve on the vent pipe ? , Mains pressure at that height cant be enough to breach a cylinder. etc ...???.

Block the vent pipe and you get this sorta craic happening:

with a few rough measurements

Needles73 · 19-05-2017 09:54PM

8Choc wrote: »

Hi, I was thinking of putting a tee connector on the mains feed to my attic tank and connecting to another tee on the output from the tank , and also putting a one way valve between the new tee on the output and the tank itself ( to stop the tank filling from the output) , has anybody ever done this ?, or know why it wouldn't work ? .I am trying to increase pressure in the house specifically the upstairs shower . As a test I fed the garden hose ( main fed ) through the upstairs bathroom window and experimented by filling a litre plastic bottle with the shower ( head off ) and then the garden hose and the hose filled it twice as fast !. Would anyone with experience know why I couldn't do this ?. Thanks in advance

Ignoring all the safety aspects running mains around the house will result in potential condensation problems. Cold fresh water into a warm house and cisterns can be an issue

8Choc · 20-05-2017 09:02AM

Do he think just supplying the shower with mains cold only would improve the pressure ? or would you just end up turning the cold down to balance with the tank fed hot etc...

listermint · 20-05-2017 09:06AM

Genuine question.

Why don't you just buy a pump like you are supposed to .

Paul Kiernan · 20-05-2017 09:29AM

I have a new build and was planning pumped DHW with a buffer tank and Grundfos pressure pump. I have a combi boiler with no immersion. As the location for the tank and pump isn't ready yet I thought (as a temporary solution) I'd connect the whole system directly to the mains which I did yesterday!

I kept the cold inlet valve to the boiler closed so only the cold is active.

As long as a tap is running everything is fine but when I turn off all the taps the pressure builds up to about 2 bar after a couple of minutes. Then when I turn on a tap, kerboom! Water shoots out under high pressure for about a minute, splashing everywhere, and then settles down!

Is there anything I can do to get my water running safely until my tank/pump can be installed?

K.Flyer · 20-05-2017 09:50AM

8Choc wrote: »

Do he think just supplying the shower with mains cold only would improve the pressure ? or would you just end up turning the cold down to balance with the tank fed hot etc...

No, it won't work due to pressure differences.
Anyway, if you turned the pressure right down to match the tank fed hot pressure, you are back to square one.

K.Flyer · 20-05-2017 09:57AM

Paul Kiernan wrote: »

I have a new build and was planning pumped DHW with a buffer tank and Grundfos pressure pump. I have a combi boiler with no immersion. As the location for the tank and pump isn't ready yet I thought (as a temporary solution) I'd connect the whole system directly to the mains which I did yesterday!

I kept the cold inlet valve to the boiler closed so only the cold is active.

As long as a tap is running everything is fine but when I turn off all the taps the pressure builds up to about 2 bar after a couple of minutes. Then when I turn on a tap, kerboom! Water shoots out under high pressure for about a minute, splashing everywhere, and then settles down!

Is there anything I can do to get my water running safely until my tank/pump can be installed?

Open the tap slower

You could fit a pressure reducing valve with a pressure gauge, but I think you are wasting your money and effort as 2 - 3 bar is normal on a pressurised system, which is what you will have when its all set up and finished.

8Choc · 20-05-2017 10:17AM

K.Flyer wrote: »

No, it won't work due to pressure differences.
Anyway, if you turned the pressure right down to match the tank fed hot pressure, you are back to square one.

Thanks, yep just thinking as well that someone could get scalded if for some reason the mains switched off !!

8Choc · 20-05-2017 10:26AM

Paul Kiernan wrote: »

I have a new build and was planning pumped DHW with a buffer tank and Grundfos pressure pump. I have a combi boiler with no immersion. As the location for the tank and pump isn't ready yet I thought (as a temporary solution) I'd connect the whole system directly to the mains which I did yesterday!

I kept the cold inlet valve to the boiler closed so only the cold is active.

As long as a tap is running everything is fine but when I turn off all the taps the pressure builds up to about 2 bar after a couple of minutes. Then when I turn on a tap, kerboom! Water shoots out under high pressure for about a minute, splashing everywhere, and then settles down!

Is there anything I can do to get my water running safely until my tank/pump can be installed?

Close the mains valve a bit , the one out on the road ? Would that work ?

Dtp1979 · 20-05-2017 10:36AM

8Choc wrote: »

Thanks, yep just thinking as well that someone could get scalded if for some reason the mains switched off !!

. I'd say your taps are to blame or the design of the basin.

Dtp1979 · 20-05-2017 10:37AM

Dtp1979 wrote: »

. I'd say your taps are to blame or the design of the basin.

Sorry wrong quote

8Choc · 20-05-2017 10:39AM

Dtp1979 wrote: »

If the mains is off then you won't have hot water. Therefore I scalding. I'd say your taps are to blame or the design of the basin.

You would have hot water cause the tank in the attic would be full ?

Taps are fine was just trying to think of a way to boost the shower a bit without buying a pump

Use mains water throughout the house

Comments