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Advice on multi-point water heating with PP-R pipes in 2-floor house


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Hi there good people. We now have the opportunity to modernize the water system and bathroom setups at GF's house. 
We think to install a multi point heater and do the plumbing  "right", simple but sustainable for the years to come.
As most sales people only preach what they sell and dont give me confidence making the right choice, your experienced input would be greatly appreciated!


The idea - see first picture - supply coming into the house on 1/2" pipe (straight from street source no active tank/pump (yet), usually good pressure), in to a Household Water Filter, then split to different rooms.

- Bathroom 1st floor bathtub/shower and wall basin sink, both mixer taps.
- Bathroom 2nd floor : shower and a wall basin sink. Also mixer taps, no thermostat mixers. 
- Aiming to plumb the warm with green PP-R 1/2" Eco pipes. Cold water with regular blue 1/2" pvc pipes.
- Total length green pipes approx 15 meter

- Thinking about a 6kW heater (MEX Centri 6R )
- Electric wire 3 x 6 mm2 , grouped with washing machine, to switch 32A in the box, about 8 meters from the water heater
- Kitchen is to be renovated too, but not expecting to use hot water there.
- Should be able to shower both upstairs and downstairs simultaneously
- Dont want lobstering the one , when the other closes their warm water tap.
- Location house in Pai, Mae Hong Son. Chilly outside temp these months but not too bad.  

* Would you think the diagram is sufficient - am I overlooking things? Would you do things different, and why?
* Thoughts on the input filter ? 
* Would the Eco PP-R be OK or strongly recommeded to use the more expensive series?
* Would 6KW be enough power? 
* Any thoughts on the MEX heater - maybe alternatives more recommended?

This post is for supply water only - for waste watering and second picture I'll post another topic later.
Thanks in advance for your thoughts!!

Pai House - TV.jpg

Pai House Diagram - TV2.jpg

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52 minutes ago, djtheoz said:

We think to install a multi point heater and do the plumbing  "right", simple but sustainable for the years to come.

If you want to do it right why use PVC at all? Do everything in PP-R. Ensure that you have the hot water PP-R for your hot supply.

 

our mains supply is ½” everything after is 32mm PP-R, and virtually every bend is a 45o using 2 for a 90o degree turn

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32 minutes ago, sometimewoodworker said:

If you want to do it right why use PVC at all? Do everything in PP-R. Ensure that you have the hot water PP-R for your hot supply.

our mains supply is ½” everything after is 32mm PP-R, and virtually every bend is a 45o using 2 for a 90o degree turn

Thanks sir for your reply - I honestly didnt even think about to do all in PP-R yet.. would you say it's worth the extra costs? Good point though.
Doesn't it lower your water pressure with 32mm ?? Or using tank with pump to buffer?

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1 hour ago, djtheoz said:

Thanks sir for your reply - I honestly didnt even think about to do all in PP-R yet.. would you say it's worth the extra costs? Good point though.
Doesn't it lower your water pressure with 32mm ?? Or using tank with pump to buffer?

There is no reduction in pressure, there is actually an increase, though it certainly could be small, compared to an equivalent length of ½”, so you loose pressure and flow. With ½”
 

You have significant friction losses with ½” pipe, many people will just use a bigger pump to overcome those losses.

 

the enormous advantage with PP-R is that the joints, done correctly, can not fail unlike PVC where there are many cases of joint failure. The fact that the joint welds the material together means that they are  irreversible . People often claim that PVC glue does the same, however I can, and have, recovered PVC joints and reused them. That is impossible with PP-R.

 

we can have showers when the power is off because of our low friction (32mm) pipe even though the pressure is about 0.4 bar from our ceiling level storage tank. I doubt that if we had used ½” and 90 degrees bends that that would be possible. 

Edited by sometimewoodworker
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Absolute minimum always upsize water pipes one step to avoid friction loss. And that alone may not be enough. A typical house may need 1 inch or larger pipes at the trunk to handle multiple fixtures simultaneously properly. There are online calculators for this. You don't want when someone turns on a garden hose or flushes a toilet that your shower stops. In Thai houses running 1/2" pipe this is what happens.

 

PPR for everything is a good choice. Always say no to PVC on all water supply unless you like toxins in the water, brittle pipes that decay in the sun, and welds that give out.

 

6KW is too weak to have two showers at once unless they are very low flow and hardly warm. A lot of people would find 6KW unsuitable for even one shower. Multi-point LPG can provide ample heat effortlessly like say units from Rinnai. And they draw almost no electrical power whatsoever; 40 watts instead of 6000 watts.

 

Toilets have integrated traps, you want p-traps on all other drains as shown. All drains need vented, not just the 2nd floor toilet. A single large septic tank will do a better job than a few little ones. And don't forget the drain field.

 

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2 hours ago, canopy said:

A lot of people would find 6KW unsuitable for even one shower.

Absolutely, our 6,500W units will struggle to get an output temperature over 36C for the next 2 months.
 

When the temperature drops under 20C i would prefer higher than body temperature showers.

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20 hours ago, canopy said:

Multi-point LPG can provide ample heat effortlessly like say units from Rinnai.

Thanks for your responses Canopy. Where would I find a unit like this? Similar to boilers like these?
6500Watts too little... so much energy and yet max 36oC ... wow. crazy too cold. Even for my farang butt!

 

On 11/25/2020 at 12:59 PM, sometimewoodworker said:

Do everything in PP-R.

- PP-R for both hot and cold - check. Will do this. We'll put pipes in the walls behind tiles so don't want to risk joint failures.. 
Upscaling diameter of pipes, at least in the storage room when splitting all directions. noted! thanks.
Will also use  45 angles only to minimize friction.

- Would the main water filter be disturbing the water flow in such system? 

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2 hours ago, djtheoz said:
On 11/25/2020 at 6:59 PM, sometimewoodworker said:

 

- PP-R for both hot and cold - check. Will do this. We'll put pipes in the walls behind tiles so don't want to risk joint failures.. 
Upscaling diameter of pipes, at least in the storage room when splitting all directions. noted! thanks.
Will also use  45 angles only to minimize friction.

Do everything in 32mm PP-R, only reduce down at the outlets. Use the correct dual outlet 

92BD689B-4FBA-4382-8A9A-88BDE379112C.jpeg.0988ca777f07bf3af2c174f540300ebe.jpeg

don’t forget to use detachable fittings at things like pumps and storage tanks, so you can take them out for service or exchange.

87635AFF-9C1E-479F-9F00-67BF1A0428B3.jpeg.653a42beb2d478dbeda76e23ce2e20db.jpeg

also for the hot supply use the correct 95o rated pipe, all the junctions are the same.

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3 hours ago, djtheoz said:

Where would I find a unit like this?

 

Example powerful multi-point LPG water heater: Rinnai REU-VR1620WG-ASN. I have a very high flow shower that outputs 1 liter per second and this unit will make it steam hot anytime of year with plenty of power to spare.

 

https://topvalue.com/130007366-rinnai-gas-water-heater-16l-reu-vr1620wg-asn.html

 

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3 hours ago, djtheoz said:

Where would I find a unit like this?

 

Example powerful multi-point LPG water heater: Rinnai REU-VR1620WG-ASN. I have a very high flow shower that outputs 1 liter per second and this unit will make it steam hot anytime of year with plenty of power to spare.

 

https://topvalue.com/130007366-rinnai-gas-water-heater-16l-reu-vr1620wg-asn.html

 

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  • 4 weeks later...

Thanks all guys, learned a lot by your responses. We made our choices.

For water heating - we will add an extra local multipoint heater, each bathroom a 6kW.
Electric wire it with 2x6 sqmm so we can upgrade to 8 kW if needed, later on. 
The main power supply will be challenged, but let's see how it works out in every day use.

For water distribution - we will do all with Thai PP-R greens. 
Bought most at Nanaphatanakit on Lazada. Best prices we've seen and good service! 
All tubes in 3/4" and at the filter trunk in 1", might do a little good covering friction loss, lets see. 
Used as little Tee's and 90-Elbows as possible, mostly 2 x 45-Elbows for corners.

For filtering, we got a big Stiebel Eltron PS, just for keeping dirt out of the system.
Might add extra carbon filtering ACB in the future.

Cheers!
 

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Some excellent advise given above. I will add your whole experience will improve once you buy and install a water storage tank, say 1000 liter or 1500 liter and a name brand water pump.  "supply coming into the house on 1/2" pipe (straight from street source no active tank/pump (yet), usually"

Your pipe size coming out of a decent pump will be a minimum of 3/4" and most often 1".  I would FILTER the water prior to storing the water.  

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