Water from Hot Water Service

[Ghoti]

Last week our old electric storage HWS died from terminal cancer (rust). We have replaced it with one of the new fancy heat pump units, complete with stainless steel storage tank.

The supplier claims that drawing water from the HWS for the ageing barrel would save heaps of electricity over the good old 300w jager heater raising the temp from cold. Yet almost universal advice from the net is not to use water from the HWS due to increased levels of copper in the water.

As far as I can tell, storage HWS use either enamelled mild steel or stainless steel tanks (mine is stainless). And most homes would use copper or poly pipes for both hot and cold water. So I struggle to see where the elevated copper levels would be in relation to water from the HWS. (unless the home is really old and still using gal pipes and a gravity fed copper storage HWS).

Does anyone have any info on this and the health of the fish exposed to water from the HWS?

Cheers,
Scott

[Nev]

Hi Scott,
I use the hws to boost the water temp for changes and have no ill effects, l've done this for many years. I'm of the same opinion as you regarding copper in the lines, maybe if your water was extremely acidic or caustic it may get trace elements of copper entrained in it. But l think illusion has a differing opinion. I'll get the water guy from nalco (water treatment for boilers) at work to explain to me about iconic copper when l see him next.

[ILLUSN]

Sorry, long answer

A very good mate of mine uses and instantaneous gas hot water system for his fish room with no ill effects. but theres a few things you need to think about.

Basicly, neutral ish cold tap water is reasonably un reactive, water flowing through your copper pipes into you hot water system wont add too much copper to the system, at least not enough that a good dose of prime wont take care of.

As the water heats in the stainless steel tank it gains evergy (hence gets hot) as the energy in a system increases so does the ability of that system to react with its surroundings.

Your heat pump moves HEAT from the air (outside the condenser) via coolant into the water, as such for every 1kw of electricity you can move up to 4kw of heat so its 4x more effective then a jager which uses 300w of energy to generate 300w of heat.

Water circulates in your heat pump storage tank over the condenser to transfer heat from the coolant to the water, if it runs through copper pipework internally the HOT water may cause a faster migration of metalic ions into the water (be it copper from pipework/condenser coils or other metals from a sacrificial anode)

The concentration of ions in thwe water will increase with the number of times water passes through the system.

If you were to put a high quality carbon filter on the out let of your system before it reaches the aging barrels you shouldn't have any real problems, just dont forget to change it every 3 months or so.

My situation is diffrent my house uses gal pipes (bout the thickness of a human hair thanks to 40years of corrosion from the inside). I'm using tap water to fill remote poly water tanks, my system will use solar energy to heat these tanks.

I'll be using heated water for tanks AND space heating (through a radiator), the water in my system will be 30C and a ph of 5.5 adjusted with HCl, Hence VERY reactive! Also i wont have a sacrificial annode as mine is an open system ( low preasure poly drums) The way way mione will work is the sun will come out and that will turn on a solar pump. The pump cycles through system (series of evacuated tubes on roof with stainless manifold and lines) till 30c then turn off. The cycle repats if (1) sun is shining and (2) water storage temp is below 30C and (3) evacuated tube temp is > water storage temp) it uses a 3 sensor system that I'm still working the bugs out of.

for winter time am airconditioner mounted in the roof cavity will suck hot air out of the roof and pump it into the fish room, this will be set at 29C

[scoob]

my house is only 2 years old and has a new HWS I'm going to give it a go and see what happens,only snag is my aging tanks are outside I'll have to get a plumber to install a hot and cold tap outside.

Illusn, your setup sounds awsome...

cheers
Mike

[swifto]

I have always used the hws which is set at(60 degrees) for aging and storing water,which my drum is set to 30dregrees so it save's on energy consumption and never had a problem,i don't think any nasties can survive at high temp in hws so should b safe.Now adays new houses use plastic hosing to run water to tapes which also why u shouldn't get water hammer.

[Ghoti]

Water circulates in your heat pump storage tank over the condenser to transfer heat from the coolant to the water, if it runs through copper pipework internally the HOT water may cause a faster migration of metalic ions into the water (be it copper from pipework/condenser coils or other metals from a sacrificial anode)

The concentration of ions in thwe water will increase with the number of times water passes through the system.

Got a reply from the manufacturer today - there is no copper or sacrifical anode in the tank! The copper condenser coil is wrapped around the outside of the tank with heat conductive paste forming a flexible bond to the tank (for maximum heat transfer) with 50mm of urethane foam and aluminium foil encasing the lot to prevent heat loss.

So, short story is the only copper is in the cold pipe to the tank and the hot pipe from tank to tap.

Cheers,
Scott

[ILLUSN]

AWESOME, you shouldn't have a problem.