Need water heater with dc pump

[Negita43]

2 hours ago, VocalNeal said:

 Rules are for the guidance of wise men and the obedience of fools.  Douglas Bader.

 

 

He must have said that when he was legless

[brianthainess]

And I thought this was about Direct Current DC.

[VocalNeal]

^ It is about a shower heater.????????

[ola33]

Ok so I can't install a water heater if it has a built in pump.

 

And in response to some, there are many water heaters with built-in pump for sale on Lazada and shopee.

 

And last I know that 4500w is for the heat I have never written anything else

 

 

[VocalNeal]

17 minutes ago, ola33 said:

Ok so I can't install a water heater if it has a built in pump.

Of course you can. Nothing to stop you and nothing bad will happen. You will simply have a constant quality shower.

[FriendlyFarang]

3 hours ago, Adumbration said:

 

Sigh....  Google check valve and then yell up the basement stairs for mummy to bring you down some milk and cookies....

I think you don’t understand how this works… Or you just want to troll.

[sometimewoodworker]

28 minutes ago, ola33 said:

Ok so I can't install a water heater if it has a built in pump.

You are misreading the information.
 

You can not pump directly from the PWA supply, there must be a storage tank between the PWA supply and any pump. As you live in an apartment it is quite possible that the apartment complex may have water storage, if so then there is no problem using a water heater with its own pump or a separate pump.

 

But despite the statements of some idiotic members if there is no tank between the PWA supply and any pump you are breaking the law of PWA regulations and risk contamination of everyone’s water supply.

 

the illustration of a toilet water bucket is rather nice  compared to sucking bacteria laden water from cracks in the pipes 

[Artisi]

5 hours ago, FriendlyFarang said:

If the pump increases the pressure on the outlet, there has to be a negative pressure on the inlet.

Not necessarily negative (and very unlikely) but certainly a reduction in the inlet pressure. 

[VocalNeal]

1 hour ago, sometimewoodworker said:

any pump you are breaking the law of PWA regulations

Will you find a link to said regulation. I can't find it. It does not appear to be on the PWA site. 

It is possible that the OP drives occasionally over the limit or pops down to the 7- Eleven without a helmet. All breaking the law. He might even buy alcohol from a village shop between 2pm and 5pm.????????

 

I don't think you fully comprehend that the supply line must be at a positive pressure for the shower heater to operate. I also don't think you have any knowledge of hydraulics or fluid dynamics. Just keep harping on about a bucket in the toilet. Which by the way needs negative pressure for the flow to reverse not the positive pressure required for the shower heater to switch on. 

 

The OP is free to do whatever he sees fit. 

[unheard]

1 hour ago, VocalNeal said:

Will you find a link to said regulation. I can't find it. It does not appear to be on the PWA site.

Here they do mention the "law".

See 3. https://wave.co.th/2021/06/12/ถังเก็บน้ำสำคัญอย่างไร/

 

 

[sometimewoodworker]

3 hours ago, VocalNeal said:

I don't think you fully comprehend that the supply line must be at a positive pressure for the shower heater to operate. I also don't think you have any knowledge of hydraulics or fluid dynamics. Just keep harping on about a bucket in the toilet. Which by the way needs negative pressure for the flow to reverse not the positive pressure required for the shower heater to switch on.

Of course the instant water heater requires a positive pressure, usually higher than 1 bar, for the pressure and flow sensors to allow the heater to function.

I have a reasonably competent knowledge of water flow and the requirements of plumbing.

You are confusing me with another poster. 

You are, from your post, totally unable to understand that a pump will by it’s very nature creates a higher pressure on the outlet side while simultaneously reducing pressure, possibly to a negative pressure, on the inlet side. This negative pressure, that is illegal, will start sucking water on the supply side from anywhere it can the toilet bucket, which was not my posting, is the least offensive source, far nastier are the cracks and badly joined pipes of the PWA, this allows wonderful anaerobic bacteria and other nastiness to be sucked back into the water supply.

 

The Thai water supply operates on a low level pressure system compared to more developed nations this means that pumping directly from the mains is more dangerous.

 

I had thought that the majority of your posts were at least competent but this one 

3 hours ago, VocalNeal said:

The OP is free to do whatever he sees fit. 

Shows you have no knowledge of the subject and a cavalier disregard of the safety of others. If you want to poison yourself, feel free. If I know of people who are trying to do the same to me I will be doing everything I can to get them provided with free food and accommodation.

[sometimewoodworker]

4 hours ago, Artisi said:

Not necessarily negative (and very unlikely) but certainly a reduction in the inlet pressure. 

With the generally low pressure of most of the Thai mains supply the chance of a pump getting the pressure negative is far from unlikely 

[VocalNeal]

53 minutes ago, sometimewoodworker said:

I have a reasonably competent knowledge of water flow and the requirements of plumbing.

Apparently not and I checked I am not confusing you with anyone else. 

 

As stated before a shower heater with an integral booster pump requires 1 psi of positive pressure to switch on. Not 1 bar. 

 

The size of the pipe in a shower heater is about 1/4  to 3/8in. The pipework in a house is usually 1 in or maybe 3/4. There is no way a flow though a shower heater at about 1.5 gpm will effect the pressure in a 3/4 to 1in pipe. A 1 in pipe at 1 psi at the open end has the potential to flow about 20 gpm. The 1.5 gpm required for the shower heater will not create a reduction in that 1psi. No matter how hard you try to believe it. 

 

You haven't grasped the non magnitude of the problem you are inventing. I believe you are confusing a pump that would supply the whole house with a tiny booster pump in one appliance. 

 

As for a cavalier attitude to the safety of others. There is no safety issue here at all. If the OP installs a water heater with a small integral pump he will not create any reduction in the pressure in his supply piping to his house. He will not increase the flow in the 1 inch pipe by the 1.5 gpm required by the heater increasing the demand to 21.5 gpm. The potential flow in the 1 inch pipe will still be 18.5 gpm or a positive pressure of about 0.8 PSI but positive non the less and sufficient for the heater. Min requirement of the shower heater is 0.7 psi  

 

 

 

[lopburi3]

11 minutes ago, VocalNeal said:

The pipework in a house is usually 1 in or maybe 3/4.

Actually believe you will find most homes here are using 1/2 inch water lines for all but main runs and not more than 3/4 inch for those.  

[VocalNeal]

^ So we are down to 11gpm with the shower heater still requiring only 1.5 gpm.

[sometimewoodworker]

15 minutes ago, VocalNeal said:

Apparently not and I checked I am not confusing you with anyone else. 

Since you quoted an idea from @FriendlyFarang I probably want some of what you are drinking or smoking.

 

19 minutes ago, VocalNeal said:

The pipework in a house is usually 1 in or maybe 3/4.

You are living in a fantasy world, the usual is ½”

21 minutes ago, VocalNeal said:

You haven't grasped the non magnitude of the problem you are inventing.

I am not inventing the legal minefield you are advocating.

Pumping from the mains is illegal.

23 minutes ago, VocalNeal said:

If the OP installs a water heater with a small integral pump he will not create any reduction in the pressure in his supply piping to his house.

he doesn’t have a house, do keep up. Or give me some of you substance.

Any pump will create a reduction in pressure, didn’t you pass physics 101?

26 minutes ago, VocalNeal said:

As for a cavalier attitude to the safety of others. There is no safety issue here at all.

Virtually all water supply authorities will vigorously disagree, many governments will also they’ll you that you are wrong.

 

29 minutes ago, VocalNeal said:

As stated before a shower heater with an integral booster pump requires 1 psi of positive pressure to switch on. Not 1 bar.

You clearly don’t understand the difference between pressure and flow, so physics 101 remedial is needed.

[sometimewoodworker]

15 minutes ago, VocalNeal said:

^ So we are down to 11gpm with the shower heater still requiring only 1.5 gpm.

And where are you getting the flow rate from??? Yes a ½” May have a theoretical ability to supply 11gpm but for that you need sufficient pressure to enable it.

 

you still don’t demonstrate that you understand the relationship between maximum potential flow and real flow at the low pressures available in Thailand.

 

for an actual flow of 11gpm you need sufficient pressure to enable it.

 

as one tag says “I can explain it to you, but I can't comprehend it for you”

[Artisi]

6 hours ago, sometimewoodworker said:

With the generally low pressure of most of the Thai mains supply the chance of a pump getting the pressure negative is far from unlikely 

A little out if context, my reference was to a water heater /pump, but you are correct in the case of a major pump being connected to the towns main. 

[Artisi]

12 hours ago, sometimewoodworker said:

With the generally low pressure of most of the Thai mains supply the chance of a pump getting the pressure negative is far from unlikely 

 

5 hours ago, Artisi said:

A little out if context, my reference was to a water heater /pump, but you are correct in the case of a major pump being connected to the towns main. 

I would also suggest that a pump incorporated into to a water heater would be unlikely to achieve any pressure reduction of significance, if at all.