Closed loop V Open loop

Alpha Heating » Technical » Closed loop V Open loop

WITHOUT PREJUDICE

The difference between "open loop" and "closed loop" water heaters

CLOSED LOOP WATER HEATING

The features and benefits of the Alpha Solar "close loop solar" water heater(indirect heating through a heat exchanger to the water in the hot water cylinder) “Like an element in a kettle”

The Alpha KT collector is premade for quicker installation on to the roof , Installation of the KT collector can be made lighter and easier if required by taking the tubes of the collector
leaving just the CPC reflector and copper tubing in place reducing the weight by ½ to (26kg) making it a one man job.

Alpha KT Solar system does not dump any energy or liquid , when in stagnation it stores the heated liquid in the expansion vessel to be used later if required when energy is needed in the hot water cylinder or the liquid will just cool and replace itself back into the flow and return piping and collector.

The KT collector has the compound parabolic concentrator (CPC) reflector , this increases the collectors efficiency be 18% , the reflector gives 300 -360 degree absorption from the tubes rather than 180 degreeslike the flat plate and other vacuum tube systems without CPC reflector technology, this in turn means less maintenance because of less tubes are needed which also means the collector is smaller and not as obtrusive on the roof.

"Closed loop" systems because of their design make it allowable to circulate and heat exchange energy into the hot water cylinder via a heat exchanger at higher temperatures for example 130-140 degrees , that gives you maximum efficiency from the energy that has been created ESPECIALLY WHEN APPLIED TO LARGE SCALE COMMERCIAL SYSTEMS where high heat levels are required..

"Closed loop" solar heating is adaptable to any liquid that needs heating due to the fact that it is an indirect heat system through a heat exchanger, for example an Alpha solar water heating system can pre-heat or heat a swimming pool , spa pool , under floor heating , radiators etc as well as domestic hot water, this shows the versatility of "closed loop" solar water heating , closed loop systems is the preferred for most of these applications

"Closed loop" systems can have biodegradable food grade antifreeze as its heating medium ,this guarantees the quality of liquid in the collector and ensures no corrosion issues with copper piping due to high heat, the antifreeze brand Alpha solar uses is TYFOCOR LS specifically designed in Germany for high temperature vacuum tube collectors with a freezing point -28 and a boiling point of 165-170 degree , because of the high boiling point less pressure is created in the collector ensuring a longer life…. "NO FROST PROTECTION required"….. one system suits all nationally .

Glycol antifreeze has multiple functions, for example….. anti corrosion inhibitors within it to lubricate pump joints and bearings and places a protective coating inside the copper piping that when the collector is at stagnation and vaporization has taken place it will stop scale build up , if using poor quality water build up of scale will happen in a short time due to the high temperature in the empty collector at this time. This phenomenon of scale or the exposure of impurities within the water applies to all types of solar panels and collectors that operate under an open loop system.

The Alpha "closed loop" system employs an element monitor by way of electrical relay via the solar controller , its purpose is to stop the element turning on straight away giving the solar collector an opportunity to heat rather than the element kicking in automatically therefore reducing solar heat time , the controller in tandem with this relay also ensures at the last moment the consumer is never without useable hot water due to the controllers software initiatives that has a bio-safe feature that eradicates the chance of Legionaires disease it also complies to NZ solar regulations.

OPEN LOOP SOLAR WATER HEATING

“Open loop" water heater.(Direct heating ..takes water from the Hot water cylinder and heats directly to the collector)Open loop solar water heating systems are generally cheaper than closed loop to purchase , due to needing less set-up componentry , a simpler pumping station and less complex solar controllers

All "open loop" systems unless they are a "drain back system" are in need of frost protection , generally preset at the controller at 3-4 Degrees to activate the pump, the result of this is the collector needs heat direct from the cylinder to keep it warm to stop the pipes from freezing and splitting(costing energy) in this process the hot water that gets circulated to the collector from the HWC is replaced with the 3-4 degree water from the collector, once again chilling the cylinder water (costing energy)

"Open loop" systems have Temperature-Pressure-Relief(TPR) valves on the collector that dumps heated water from the hot water cylinder when the collector reaches summer stagnation. TPR valves open up at temperatures around 95deg C. wasting precious water and stored energy that has been created from solar heating and electrical or gas backup, (note: this type of system has been banned in Brisbane and the Gold coast of Australia due to it wasting too much water and energy)…this is only my opinion but my belief is the ban within time will more than likely apply across Australia due to their severe water shortage , the correlation here is NZ has basically adopted the Australian Solar regulations and I would expect NZ to follow
suit at some point in time. I predict within 10 years.

Where poor water quality is in existence heat pipe collectors that are installed as an Open loop solar water heater shoudn't be installed , at the hottest point of heat exchange in the collector exposes impurities within the water being heated , in an open loop system with high lime content for example creates a lime scale that invariably ends up being caked on the heat exchange point , when this happens the exchange of heat is poor, to cure this problem some companies recommend you install a water softener.

Some "open loop" systems turn the thermostat setting for the element down to 55 degrees without any other element monitoring . When water is used from the cylinder cold water is injected to replace it this in turn cools the thermostat activating the element therefore with this theory the solar panel is only active to contribute heat to the HWC when it reaches temperatures above preset thermostat setting 60 degree. Rheems (enameled) cylinders have a maximum recommended storage temp safely of 70 degrees therefore generally open loop systems as I have described only contribute maybe 20 degrees in this common case scenario.

The Alpha closed loop system is totally automated , open loop system providers instruct owners to turn the power on and off at times , the elderly or uninterested do not want this hassle they just want their water hot with little effort or monitoring on their part.

"PRICE TO SOME EXTENT DOES DICTATE QUALITY" the answer here is you get what you pay for….buyer beware "DON'T EXPECT TO BUY A FERRARI FOR MORRIS MINOR PRICES" ALPHA SOLAR OFFERS THE CONSUMER AN INTRINSINCLY EFFICIENT AND SUPERSAFE SYSTEM WITH YEAR ROUND USAGE ALONG WITH A COMPREHENSIVE WARRANTY.

Alpha Heating » Technical » Closed loop V Open loop