QUOTE(wa1k3r @ Nov 19 2013, 11:13 PM)
did quite a bit of reading indeed
main reason why i'm interested in these hybrid system is i know majority of my electricity consumption now is Air Con and Water Heater (am using electric storage water tank now)
and once moved to the new place, i know the AC consumption is gonna increase tremendously (in law will be around to take care of my kids during the day)
so, any ways of saving the cost of either one interests me.
i'm aware not many ppl actually venture into these hybrid, just dunno why. i've sent microsolar an email enquiry. see what's the reply like.
ohh, btw, to answer your question, even if you dun switch on AC for a day, you're still getting the solar water heater function...in reality, unless the temperature outside drops to <10deg C, there's no way the AC is not switched on. even during rainy days the AC is switched on
re the pipes, price is one major concern. was told the PB1 pipes are much cheaper than copper pipes. also, am extremely worried about the jointing quality as these pipes will all be buried/concealed behind... wall. my friend's place uses ABS pipes (cold water) and less than 1 year move in, about 2-3 leakages at multiple locations. the new plumber now recommend he replace all ABS with HDPE pipes
it seems there's a lot of issues with copper pipes (hammer noise, creep etc) that ppl just live with.
i might just give the PERT pipes a try..depending on the cost of course...
thanks for your comments!!!
wa1k3r, your proposals are sound for landed: combining solar water heater (SWH) with air cond water heater (ACWH) as backup. With the humidity here, yes even I turn a/c on rainy days just to feel dry. One other caveat: unless the product is rated as such, only R22 refrigerant based should be used. R410a inverters may not be suitable. Except of course you're thinking of solar air conditioning which uses their own unit.
As far as I know combining SWH with ACWH is ideal, on paper. ACWH works fine on its own in condos, shoplots and hotels. On implementation of SWH with ACWH, it's not trivial task as a lot of consideration is needed to ease maintenance and avoid future pains from leakages much later. At this point after much pondering and opinion by plumber sifus some either consider SWH alone with a sole backup electric water heater (EWH) or just two ACWH with no solar heater to avoid the complications that arise or just go with solar air cond plus storage water heater.
A. Placement: SWH feed into ACWH or the other way round.
Advantage and disadvantage of both is:
SWH -> ACWH
1. On cold days it downmixes temp of ACWH which means unless a/c is turned on, there's virtually no hot water.
2. On hot days it upmixes temp of ACWH which is not ideal. This is the greatest disadvantage of this placement and why it should not be considered. It will take its toll on the AC compressor which will work even harder.
3. Most cases, it's easier pipe joints from SWH outlet (copper) to ACWH inlet (copper) without hassle of a union joint. Explained later.
ACWH -> SWH
1. On cold days, if a/c is turned on, it brings up the temp of the water in the SWH just like a backup water heater.
3. On hot days, it supplies the SWH with pre-heated water making hot water within a short time.
3. Union joints required as the material use to join disimilar pipes. The use of union joint pipes is crucial connecting between ACWH and SWH as most ACWH outlet are copper and some models of SWH specify stainless steel inlet. Otherwise rusting will occur as one becomes the sacrifical anode. This is where most leakages occur after a long while. So, care has to take this into account and have stop valves strategically located to faciliate replacement. One model of ACWH (Elton Ignis) have a 4 branch manifold to distribute up to 4 outlets. Unless this can be remove to just provide a single outlet the other three either has to be closed off or use for kitchen, laundry and downstairs bath. Complicated?
4. Potential leakage spots - water pump pressure to drive water to SWH from ACWH may cause leaks over time due to water hammer issue esp if a distribution manifold is present and not removable. As such avoid these models which may be suited for condo, apartments and hotels.
B. Tank size
For one ACWH, a branch off from the water pump cold supply plus a check valve is needed so that the hot water does not flow back into the cold supply line.
Tank size should be a function of AC HP, duration of AC usage and frequency of hot water usage. Higher AC HP and longer usage duration needs bigger tank to absorb the waste heat. Otherwise the AC will work harder after 4 hours. There's a trade off point and all this has to do with water volume and how much heat it can take off the compressor. On cold days, hot water is used more but on hot days? Unless hot water for kitchen, laundry down stairs bath is considered which lends to higher installation costs.
Complication comes when say you require two ACWH to maximise heat recovery from 3 BRs and living room. Since most tank can only take two AC compressors. In this case another 'surge tank' like an Electric or gas WH tank needs to be there to hold pre-heated water before feeding it to SWH. Here the water pump needs to be strong to drive cold water through the ACWH inlet, outlet and finally into SWH tank. It needs to be pump driven, making the system pressurized. Where there is pressure, potential for leakages abounds. Check valves, stop valves and pressure reducing valves are needed to ensure constant water pressure that does not exceed SWH and ACWH structural pressure limits. This itself already lends to pontential leakage spots.
C. Water pump
Spec is crucial. Any branch off to drive to ACWH reduces cold water pressure to POU. For one, the water pump needs to feed cold water in and drive the heated water out to the solar heater in the roof. Something like a Softjet 4 or equivalent is needed even for a 2 bath as each ACWH behaves like a POU.
D.Plumbing and plumbing material spec
The planning for the plumbing is crucial esp if ACWH should come later after the solar water heater is installed. Specifically check valves and bypass from water pump or incoming Syabas line should be planned in the design. Strategically placed stop valves also for troubleshooting and maintenance with careful selection of plumbing material to ensure durability of piping and minimise leakges esp from a pressurized system.
Pipe options to consider possible could be:
Cold
Hansen pipes. Sold here as well.
Cold inlet supply to xWH - follow manufacturer spec
Hot - I would agree with steve8 on copper or stainless steel. These last longer. If your place has long runs from hot water down pipe to the toilets, consider insulating them with a urethane sleeve.
If the house is old development like before 1990s, chances are GI pipes may still be in used. These are a ticking time bomb as mine has proven to be. Had to have an ugly pipe running along the wall as mine leaked after two years of using water pump. Hammer noise is usual but if the unit is old and if the old plumbing is being replaced, consider segregating WC from bath/shower/basin from water pump. This protects WC supply inlet from pump pressure surge which leads to leakages and overflows of the water cistern. PVC for WC line is ok with one line from tangki supplying both bathrooms with a stopcock at each WC inlet POU and one stop valves at each branch tee. Why should refilling toilet water run the pump unnecessarily?
Now you know what's ahead of you if this is the considered path, I hope you have fun and happy renovating plus share the journey too.
Nov 6 2011, 12:24 AM, updated 3y ago
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one cylinder can last very long too (for us around 2mths for the water heater alone). seems much cheaper than solar water heater to me.
. Oh, electrician also under him 
Not cheap.
the mixer must be something wrong,
Can tell us more about it? How to convert and what parts need. 
A drop of anti termite solution makes one little of water whitish and it remains and stays white for months. Someone accidentaly pour in some termite soluton. Ok, not to frighten you too much. Does the water smell? If you have no good nose get children to smell. No wind no fan bring the water close to your nose.
tired and hungry. As you step into the shower room, wah lah heavy warm rain pouring on your body 
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