View Full Version : Water heater for low water pressure

03-05-2004, 07:06 AM
Sadly for months now, the electric water heater in our house has been useless as the Subang Jaya mains pressure is too low to trigger the heating mechanism.

Can anyone confirm if water heaters can run off tank water? I hear there are models with built in pumps and can work with tank water rather than mains water.
Recommendations most welcome.

03-05-2004, 11:15 PM
Mains water too low to activate the water heater switch? My sympathies to you if that is true because then the water from your mains is probably so weak that the water won't even get up to the water tank! Think about that - something tells me the logic is amiss here.

As for feeds from the water tank itself, the pressure certainly isn't enough for the upstarirs bathrooms because the difference in height of the water tank from the upstairs bathroom shower installation is probably only less than 6 feet or 2 meters.

The best solution is to get a pump to be installed between your water tank and the bathroom pipings. I got a Grundfos pump which is certified to serve 2 bathrooms. I now have excellent pressure on all my upstairs bathrooms. I keep the downstairs bathroom off the pump because the height of 15 ft or so is sufficient head for a reasonable pressure.

Since I do not use the shower heaters with pumps included, I am in no position to advise on that matter. I had asked the retailer once about the pump and I got a wishy-washy answer which I translated to mean that it isn't much of a device and we shouldn't expect miracles. Actually, if you had a look at a Grundfos pump (even the smallest one) you will realise that no way anything added to the water heater can be expected to perform like a real pump.

BTW, I am not a hardware dealer nor do I market pumps. I use Grundfos as an example because they seem to be the well-known one.

04-05-2004, 08:55 AM
Yes. Instal a pump in the water tank. I have not used one, but have heard friends using them and it solve the problem.


04-05-2004, 02:50 PM
It's certainly a bad idea to connect an instant water heater directly to the main supply.
I did that once before and the brass cylinder inside the water heater swelled up progressively. I had guessed that this was due to excessive water pressure at my former home. Mains water pressure will differ from home to home, so it may or not happen to yours. Having said that, it's still risky to contemplate on such unless one knows how thick the brass cylinder is or the quality of it. I take it as most will not withstand anything more than 40 - 50psi.
I'm not sure of the output pressure of an installed domestic pump but I should think it's at much safer levels than the mains.
My present home shower water pressure is pathetic despite the home only less than 10 years old and fitted with PVC piping.
PVC pipes too may incur leaks if connected to the mains.

04-05-2004, 04:42 PM
There should'nt be any problem connecting directly to the mains. The connection is usually done in series with a control valve where you set the water outlet flow. If the pressure is indeed that very high , you would naturally reduce the water flow thereby reducing the pressure to the heater . Unless ... unless .. your installation of the control valve is at the heater outlet , then you are putting yourself at great risk of being scalded or worse an explosion ! .
Always remember that the heater outlet also act as a over pressure release valve.

04-05-2004, 09:40 PM
I am presently using a water heater with integral water pump.
Heater brand is AERON..malaysian made with heater from

I installed it myself for the upstairs back bathroom..
Water pressure at the outlet head is good, it can even be adjusted to give you a massaging spray of water!

Bought it from KK Aircon/Electric..
No 7 Jalan USJ 18/9
Fon: 80232202..

They also have water filters for the house incoming mains..

One more method is to install a check valve from the mains incoming pipe and the water tank outlet going to the upstairs bathroom. If mains pressure is available, the water going to the upstairs bathroom wud be from the mains..in situations where there is low mains pressure..u still will get water from the tank, but your water heater will not work.
I have done this to my master bathroom upstairs.
Had to pay RM200 to a plumber to do this method..the check valve only costs RM20..!


04-05-2004, 10:52 PM
Chang, how much does it cost to install Grundfos domestic pump that you have? I may consider that solution instead of getting 2 new units of water heater with built-in pump.

05-05-2004, 12:01 AM
have seen a number of heaters with built in pumps, the last time i went to a major electrical superstore - think it was harvey norman's or best super denki.

also, i have a simple national water heater which is connected to the water tank supply in my downstairs bathroom. the output pressure is quite low, but the inlet pressure is sufficient to activate the heater. it works great!

05-05-2004, 12:33 PM
If your heater was usable at the time of installation but now not, please check for leaks. Your direct supply may have sprung a leak.

Please check the water pressure. to do that, remove the inlet connection and turn on the water. if the water pressure is strong at that point, check is the main inlet filter to the instant heater. A friend's heater had the same problem. There actually 2 filters in the inlet side of the heater. 1 is easilly accessible from the outside but the other is not. This is usually located just next to the control tap. Clean those filters.

05-05-2004, 11:45 PM
I paid RM1,100 for the Grundfos CH2-30PT in Oct 2003. I don't know how much it will cost now - probably more because of the drop in Ringgit's value. It was also on offer then.

It should be cheaper to get the heaters with pump as opposed to heaters with no pump plus a Grundfos. However, do remember that with the Grundfos setup, you put good water pressure to all the taps in the 2 bathrooms, not just the shower heater. Pressure at the bidet tap is a must have if you use such taps ;)

Do take note that you need to follow the instructions (make sure the plumber follow it) for the installation as Grundfos recommends check valves (bypass valves) to be placed before and after the pump so that in the event there is no electricity, the tank water can bypass the non-functional Grundfos and still ensure water supply to the bathrooms from the gravity feed from the water tank.

Do note that besides the plumber, you will also need to cost in an electrician to install electrical supply to the pump in your attic.