24v pump for hotwater

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24v pump for hotwater

Postby jdaley » Sun Oct 14, 2012 8:15 pm

Are there any 24V dc pumps which will tolerate hot water. I have a gravity system for solar hot water and the tank is not high enough. So, I am thinking of installing a self starting pump to pressurise the hot water on demand. Is there anything that actually works.
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Re: 24v pump for hotwater

Postby Gordon-Loomberah » Sun Oct 14, 2012 9:48 pm

Perhaps try a washing machine or dishwasher pump operated by a 24V motor, driven by a chain or pulley. 100 -300W motors are available for a good price from places such as Oatley Electronics.
For a bit more money, I think there are low voltage cast iron pumps that will handle water at around 100C.
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Re: 24v pump for hotwater

Postby Tracker » Mon Oct 15, 2012 6:40 am

.
Why 24v.. I wonder ..
What about mains? You can buy cheap booster pumps on AC. And cheap inverter modules are common.
Just thinking that a dedicated DC pump will be.very expensive.
Gordon's thought would be an alternative .. what about an old Simpson mechanical Pump. You could keep an eye open for junked machines .... 164. 175. Or malleys, or old kleenmaid
But what temperature are we talking about .. tempered or Tank output ..
..
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Re: 24v pump for hotwater

Postby jdaley » Mon Oct 15, 2012 11:19 am

I mentioned 24v becuase that is all the power I have being a self contained solar place.
I am aware of Sureflow pumps which I have used for 40 years with cold water, but they have a rubber pressure washer and I am concerned hot water may harden the washer.

I am talking about hot water from the storage tank at about 100 degrees celcius.
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Re: 24v pump for hotwater

Postby Tracker » Mon Oct 15, 2012 2:36 pm

.
Yes - I do see the dilemma.

The OLD mechanical pumps ( with an Oatley 24V motor.)... well in reality I don't know how they would work at 100c.. They are not designed to work there..
All you could do is to try it..

Just a thought - could a tempering valve help things, or do they not work with gravity feed HW..?
ie. tempering valve then the pump to give pressure.. I suppose that if the pump is sucking from the storage tank, then it might actually make the tempering valve work better..
What do you do for COLD water.. is that tank and another pump..?
..
.
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Re: 24v pump for hotwater

Postby Gordon-Loomberah » Mon Oct 15, 2012 3:25 pm

Tempering valves need a certain amount of pressure to work. If there isn't enough pressure for a shower, which really only takes 2 or 3 metres of head, then a standard tempering valve wont work, although there may be some low pressure ones available- but they would need larger diameter pipes to work at all.

You could probably pick up a suitable 2nd hand pump from a washing machine repair shop for free to test it out, although they are not going to deliver much pressure- but some is better than none...
Maybe you should just lift the hot water tank up a bit- perfectly satisfactory showers can be had with a hot water tank in the roof space of a house with 2.4m ceilings.
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Re: 24v pump for hotwater

Postby jdaley » Mon Oct 15, 2012 3:44 pm

I use a 24 V Sureflo pump for the cold water and have for 40 years.
Currently I only have about 1m head for the hot water. I am thinking of lifting the tank by building a tower which would double as a ventilation tower. But in the meantime and good head in the shower would be very nice.
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Re: 24v pump for hotwater

Postby Gordon-Loomberah » Tue Oct 16, 2012 3:12 pm

I'm pretty sure you would damage the existing pump with near-boiling water from an unregulated hot water system.

You could always use a cast iron/steel (or whatever they used) pump that will definitely handle ~100C water- the oil pump from an old Holden (and probably many other makes too) engine could be bought from a car weckers for not much money, and given a good clean out. I'm not sure if rust would be a problem with them though- it depends a bit on water quality and the quality of the steel in the pump. They should deliver plenty of pressure when hooked up to a suitable 24V DC motor, but would need a bit of modification to hook up to the water supply.
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Re: 24v pump for hotwater

Postby brendanh » Tue Oct 23, 2012 9:19 am

Try here. These are automotive radiator pumps. So they are made for hot water.

http://www.daviescraig.com.au/Electric_ ... tails.aspx
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Re: 24v pump for hotwater

Postby Tracker » Tue Oct 23, 2012 10:09 am

brendanh wrote:....These are automotive radiator pumps......

Good Find - i have never seen the B4..
Had trouble working out how it worked.. Looks exactly like a commercial DishWasher pump - minus the drive motor, but, I presume the motor is actually built in..
..
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