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Author Topic: Mixing hot water from gas geyser with cold water.  (Read 720 times)

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Offline Butch

Mixing hot water from gas geyser with cold water.
« on: July 30, 2018, 03:22:59 pm »
I'm sure I've seen this discussed here, but can, for the life of me, not find the post.

I have a booster pump that supplies about 2bar pressure (I'm sure that's what it is rated at) on my water pipes. This also feeds an outside gas geyser which heats the water for the shower and kitchen sink.

For the shower, I just brought the hot water pipe from the geyser and the cold water pipe from the booster pump together with a T and then a single pipe going to the shower head. You start the shower by opening the hot water tap first, which gets the geyser going. When the water is hot enough, you open the cold water tap, but nothing happens until you open it far enough. Then the hot water stops and the geyser shuts off. It is as if the pressure from the hot and cold water work against each other and will only allow either to flow.

Does anybody have some advice on how to fix this?
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Re: Mixing hot water from gas geyser with cold water.
« Reply #1 on: July 30, 2018, 04:26:05 pm »
My guess is it is pressure related. I run the same setup as described but from municipal mains. In peak hour the geyser would shut of like you said, I made the sum the the pressure is then to low to keep the valve at the geyser open.

Check your pressure pump also. 2 bar should be enough though.

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Offline Sláinte Mhaith

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Re: Mixing hot water from gas geyser with cold water.
« Reply #2 on: July 30, 2018, 04:37:44 pm »
Yes, I agree it is pressures.  You need to get the pressures balanced.
« Last Edit: July 30, 2018, 09:43:46 pm by Sláinte Mhaith »
 

Offline Casting from Turd

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Re: Mixing hot water from gas geyser with cold water.
« Reply #3 on: July 30, 2018, 05:16:54 pm »
Jis Bitch.
Make sure your supply to your gas geyser is not on the same feed line to your cold water tap in the shower. If you open the cold water it takes away feed from your geyser causing it to shut off as there is not enough pressure.
My geysers run on a pressure/booster pump as well.
I take the geyser supply straight from the mainline. The main line is a 32mm pipe. I then reduce that to a 22 mm copper pipe and at the geyser it reduces to a 15mm. This creates a manifold like system on the supply side.
The hot water supply from the geyser to the tap is a 15mm copper pipe.
Run the cold water as per normal to the cold water tap.

If you were closer I would come and do it for you.
The thing is to balance the incoming pressure. IE"the cold water to the shower tap does not take any pressure away from the geyser feed

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Offline Butch

Re: Mixing hot water from gas geyser with cold water.
« Reply #4 on: July 31, 2018, 09:15:49 am »
Thanks, Turd. I think you nailed my problem.

I have a 22mm pipe coming from the booster pump with several T's feeding cold water taps. At the end of the line a 22mm copper pipe feeds into the geyser with a 15mm copper pipe outlet to the hot water tap.

I'll give you a call once the coffee kicks in.
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Offline Hanno @ Mad Macs

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Re: Mixing hot water from gas geyser with cold water.
« Reply #5 on: July 31, 2018, 09:22:51 am »
I have a similar problem.

To compound the problem I have a mixer tap in the shower. So as you start to turn towards the colder side it also starts to throttle the warm side. until the whole things stops and you shower in cold water.

I have just gotten to the point where I set the geyser temp to a useable temp and just open the hot water.
As summer approaches I start to turn the geyser temp down.
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Re: Mixing hot water from gas geyser with cold water.
« Reply #6 on: July 31, 2018, 10:34:49 am »
Hanno, your solution is the most cost effective way to run a gas geyser

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Offline Butch

Re: Mixing hot water from gas geyser with cold water.
« Reply #7 on: July 31, 2018, 12:14:31 pm »
That is what I also do at the moment, but the dishes need hotter water, so you turn up the heat for dishes and forget to turn it down for shower. The next morning you get a hot surprise and have to run outside in the cold to turn it down.
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Offline Operator

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Re: Mixing hot water from gas geyser with cold water.
« Reply #8 on: July 31, 2018, 12:50:47 pm »
Boereraat:   Vat 'n ordentlike groot tang and knyp die koue water pyp so effens toe. Dit sal dalk nie volgens voorgeskrewe plumbing
riglyne wees nie, maar dit mag die waterdruk aan die koue water pyp verlaag   :patch:
 

Offline Butch

Re: Mixing hot water from gas geyser with cold water.
« Reply #9 on: July 31, 2018, 12:58:08 pm »
Dis onwetlik daai. Hier bou ons streng volgens planne en regulasies. Ons bou en wanneer daar vir planne gevra word, maak ons seker iemand kan die planne teken presies soos wat daar gebou is.  :biggrin:
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Re: Mixing hot water from gas geyser with cold water.
« Reply #10 on: July 31, 2018, 01:09:03 pm »
Dis onwetlik daai. Hier bou ons streng volgens planne en regulasies. Ons bou en wanneer daar vir planne gevra word, maak ons seker iemand kan die planne teken presies soos wat daar gebou is.  :biggrin:

Daar is nie 'n pressure reducer wat jy in-lyn kan installeer nie..................en binne wetgewing is nie?

Mens kan so maklik hierdie tipe waterpype las en pas met bolt-on/bolt-off plumbing solutions.
« Last Edit: July 31, 2018, 01:09:47 pm by Operator »
 

Offline Sláinte Mhaith

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Re: Mixing hot water from gas geyser with cold water.
« Reply #11 on: July 31, 2018, 02:11:48 pm »
Dis onwetlik daai. Hier bou ons streng volgens planne en regulasies. Ons bou en wanneer daar vir planne gevra word, maak ons seker iemand kan die planne teken presies soos wat daar gebou is.  :biggrin:

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Offline Hanno @ Mad Macs

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Re: Mixing hot water from gas geyser with cold water.
« Reply #12 on: July 31, 2018, 02:20:06 pm »
That is what I also do at the moment, but the dishes need hotter water, so you turn up the heat for dishes and forget to turn it down for shower. The next morning you get a hot surprise and have to run outside in the cold to turn it down.

So what I do if I need HOT water is to open the hot tap and then close it slightly reducing the flow through the geyser thus expanding the heating time. Gives me good hot water for the dishes.

And slightly colder water for the shower.
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Offline Welsh

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Re: Mixing hot water from gas geyser with cold water.
« Reply #13 on: July 31, 2018, 05:13:37 pm »
Booster pumps? How low is your water pressure?  :sip:
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Offline Butch

Re: Mixing hot water from gas geyser with cold water.
« Reply #14 on: August 01, 2018, 07:33:32 am »
Booster pumps? How low is your water pressure?  :sip:

Water comes from a borehole into a JoJo tank that is slightly higher than the taps, so not enough pressure to activate the geyser and cold water flows at a leisurely pace without the booster pump. When I grow up I will build a header tank that is high enough to supply the pressure I need without the pump.
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Offline Butch

Re: Mixing hot water from gas geyser with cold water.
« Reply #15 on: August 01, 2018, 07:51:37 am »
Anyway, I got a few good tips from the Turd that I will implement in the new kitchen and bathroom that I'm building. Will post pictures and instructions when it's done.
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Re: Mixing hot water from gas geyser with cold water.
« Reply #16 on: August 01, 2018, 08:08:21 am »
Booster pumps? How low is your water pressure?  :sip:

Water comes from a borehole into a JoJo tank that is slightly higher than the taps, so not enough pressure to activate the geyser and cold water flows at a leisurely pace without the booster pump. When I grow up I will build a header tank that is high enough to supply the pressure I need without the pump.

OK, wasn't thinking about boreholes.  :thumleft:
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Offline JacquesM

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Re: Mixing hot water from gas geyser with cold water.
« Reply #17 on: August 07, 2018, 08:43:16 pm »
We use a separate 6 l/m gas geyser for the kitchen, set at 55°C.

The 8 l/m one supplying the bathroom is set at 44°, so there's no need to open the cold water.

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Offline 73 Peanut

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Re: Mixing hot water from gas geyser with cold water.
« Reply #18 on: August 07, 2018, 09:07:39 pm »
First of all two bar is very low pressure so that could be the cause of all your problems if you do not have a large enough pipe feeding the system . Most small pumps have a 1 inch in feed and outlet.  You can  not have a smaller pipe feeding the pump or it will cause issues as well.  If you feed off a tank remember you get about 1 bar per every 10 meters.  I suggest running a pump that supplies at least 3 bar running pressure then you don't have issues . Check to see if there isn't a filter just in front of your geysers inlet. Could be some dirt restricting the flow .