Browse Forums Bathrooms and Laundry 1 Feb 23, 2010 9:44 am Call this part 3 of 3 of dealing with a useless plumber! After moving in, I noticed that when using only the hot water in the Kitchen or Laundry mixers to wash up that the water would go cold after a while. It didn't come back until the tap was turned off and then back on again. I never had a problem with the shower though and thought that because I wasn't using just hot water that the issues in the kitchen were due to the HWS not being able to supply enough hot water? The HWS is a technika 26L unit. It was supplied by the plumber after a mix up. I said I would supply a Bosch or Rinnai unit (which ever had wireless controllers as I'd forgotten to pre-wire fro the controllers upstairs), but he'd already rocked up with the technika and fitted it... Anyway, questioned the plumber about the hot water issue and instantly he had an answer. He claims that the restrictors in the taps heads cause the water pressure to drop too low and the HWS switches off. He said he removed them from the shower heads when they were fitted and that is why I never noticed a problem in the shower. When he came out to address some other issues, he also removed the restrictors from the laundry and kitchen taps. In hindsight, if I knew how they were fitted, I wouldn't have let him do it. ie, they were not removed in a way that would enable me to refit them. So if I want them back its replacement parts and/or new tapware. Testing the kitchen after his so called correction, has resulted in no fix. Because there is no restrictor I had the tap running at what I believe was a more than adequate pressure to wash the dishes and the water still went cold. Based on his logic of pressure, I'd need to have the tap running wide open to stop the HWS shutting off which is rubbish. I feel like I have been shafted the big one here. Has anyone experienced anything like this? There must be 1000's of houses with instantaneous HWS's and water efficient taps that don't have problems. My plumber is making it sound like instantaneous HWS's are not compatible with water efficient taps. Surely not? Re: Instantaneous HWS req certain pressure to maintain hot water 2Feb 23, 2010 10:13 am Yes the problem can be caused by the restrictor, but not totally its fault. The issue mainly ****** with new house because there is sometimes some contaminates in the pipes. Then the restrictor easily becomes blocked, there isnt enough pressure and the hot water cuts off. So basically best to get to the root cause of the issue. If everything works ok there shouldn't be an issue. Make sure the tap underneath the sink is opened fully, and that there are no small blockages, which get caught in the tap. Re: Instantaneous HWS req certain pressure to maintain hot water 3Feb 23, 2010 11:25 am We had the same issue in our last house and got the same answer. It also took forever for hot water to come through to the kitchen because it was so far away from the hws that I just started using the kettle for it instead. Re: Instantaneous HWS req certain pressure to maintain hot water 4Feb 23, 2010 11:37 am borg Make sure the tap underneath the sink is opened fully I have them about half way at present because if they are fully open and someone flicks the mixer to full, it will come out so bloody hard that it sprays water everywhere!! Ms Builder It also took forever for hot water to come through to the kitchen Once it has turned off and I have to flip the tap on/off it takes 20-30secs to come back which isn't so bad I guess. Just wish it didn't turn off in the first place! Re: Instantaneous HWS req certain pressure to maintain hot water 5Feb 23, 2010 12:07 pm dave- borg Make sure the tap underneath the sink is opened fully I have them about half way at present because if they are fully open and someone flicks the mixer to full, it will come out so bloody hard that it sprays water everywhere!! Ms Builder It also took forever for hot water to come through to the kitchen Once it has turned off and I have to flip the tap on/off it takes 20-30secs to come back which isn't so bad I guess. Just wish it didn't turn off in the first place! Hi Dave, not having the taps underneath fully open is fine normally. However if something is lodged inside the tap due to the small opening it may be what is causing your issues. Re: Instantaneous HWS req certain pressure to maintain hot water 6Feb 23, 2010 12:17 pm If the restrictors have been removed though, small particles blocking them is obviously not the cause. There must logically be something else wrong with your kitchen plumbing. Time to get the useless plumber back...? Re: Instantaneous HWS req certain pressure to maintain hot water 7Feb 23, 2010 12:20 pm kek If the restrictors have been removed though, small particles blocking them is obviously not the cause. There must logically be something else wrong with your kitchen plumbing. Time to get the useless plumber back...? Kek, if the taps are not opened fully there is a small possibility that the blockage is occuring in the tap (as in the tap under the bench) Re: Instantaneous HWS req certain pressure to maintain hot water 8Feb 23, 2010 12:27 pm borg Kek, if the taps are not opened fully there is a small possibility that the blockage is occuring in the tap (as in the tap under the bench) There is plenty of water flow, even with the mixer at half. Highly doubt there is any blockage. Re: Instantaneous HWS req certain pressure to maintain hot water 10Feb 23, 2010 2:39 pm borg you only need at least 2.5 litres per minute. What else could it be i wonder?? I'd love to know! EDIT: Rang Bosch sales to enquire if their units are any better and was told that all their instantaneous require 7.5L/min for taps and 9L/min for showers to keep the unit running? That doesn't sound right to me? Interestingly their units specs state a Min. inlet water pressure of 100 kPA which I assume is the rate of flow required to keep the unit running? If so, my unit in comparison has a sticker saying 210 kPA min which seems like a huge difference? EDIT #2: The range specs (http://www.bosch.com.au/content/languag ... _specs.pdf) have another figure which is what I think I should be looking at. "Min. constant water pressure for Max. flow = 230 kPa for the 26L/min unit. However interestingly enough, the smaller 21L/min unit requires only 130 kPa. So maybe I'd have been better of with a smaller unit? Re: Instantaneous HWS req certain pressure to maintain hot water 11Feb 23, 2010 3:32 pm There are a few possible causes. The most obvious is the flow restrictors, but you seem to have addressed this issue. Next is the gas pressure. Is it enough? If the gas pressure from the meter isnt high enough it can cause this type of problem, but usually not just with one fixture. It can be adjusted at the meter. It can also be adjusted at the unit. But If it was a gas pressure issue, it would affect the entire house. Have someone stand by the unit and then stand by the kitchen tap. Turn the hot onat the kitchen. the person by the unit should here it switch itself on. There will be a clicking noise. If the clicking noise fails to sound, you have a flow problem, in that theres not enough flow to activate the electronic gas igniter. The fact that you have a long run to the kitchen may also have accentuated the problem. Your brilliant plumber may have squashed the pipe somewhere, further restricting the flow. You can measure the flow coming out of the tap using a bucket and clock. I've put in heaps of instantaneous units and im not familiar with technika. i checked with my supplier and he said they were **** and almost impossible to get after install. service on. If I were you, Id put it back on your plumber he installed it. As a plumber, if I install something, it my responsibility to make sure it works correctly. Either I fix it or the manufacturer does a seervice call. If your plumber says the flow isnt adequate its up to him to prove that. Its easy to test and do this. Then its up to him to provide you with an adequate flow....if he did the install. PS It could also be the flick mixer tap itself, in that the inbuilt non return valves arent operating causing a crosssed connection and backflow. But this would only happen when you mix hot with cold, not on hot alone. Regarding the mini isolating valves. Always use ARCO. They have an inbuilt non return valve and never leak. Re: Instantaneous HWS req certain pressure to maintain hot water 12Feb 23, 2010 3:57 pm vvs mand There are a few possible causes. vvs mand But If it was a gas pressure issue, it would affect the entire house. vvs mand Have someone stand by the unit and then stand by the kitchen tap. Turn the hot onat the kitchen. the person by the unit should here it switch itself on. There will be a clicking noise. vvs mand The fact that you have a long run to the kitchen may also have accentuated the problem. vvs mand Your brilliant plumber may have squashed the pipe somewhere, further restricting the flow. vvs mand I've put in heaps of instantaneous units and im not familiar with technika. vvs mand If your plumber says the flow isnt adequate its up to him to prove that. Its easy to test and do this. Then its up to him to provide you with an adequate flow....if he did the install. Re: Instantaneous HWS req certain pressure to maintain hot water 13Feb 23, 2010 4:35 pm Dont accept the tecnika. It will end up being the bain of your existence. Insist upon something with a five year warranty. Im guessing its something to do with the unit not likeing your flickmixer. Try turning the cold off at the wall under the sink and then turning on the hot on the flickmixer. Ill bet it activates the hot water unit and you get hot water. . If everything else is activating your heater, but the kitchen isnt and youve removed restrictors, youve got to think that it must be the tap and the hot water unit not liking each other. Thats one reason i like arco mini isolating valves. Because they have a non return valve in them, you dont get crossed connectionms or backflow problems. Either way, dont accept the hot water unit from him. Re: Instantaneous HWS req certain pressure to maintain hot water 14Feb 24, 2010 11:31 am vvs mand It will end up being the bain of your existence. I'm already there! Rang technika and their "tech support" people didn't even know they sold a HWS unit!!! Still waiting for a call back from someone who can actually help. Re: Instantaneous HWS req certain pressure to maintain hot water 15Feb 24, 2010 2:25 pm vvs mand Im guessing its something to do with the unit not likeing your flickmixer. Looks like you hit the nail on the head. Had a chat with a bloke at technika technical support and he asked if I had low pressure taps fitted. He lost me in the jargon but I recall 30kPa or something like that and normal tapware not being suitable for use with the unit. I'm going to get the plumber to speak with technika and resolve it. See where I get. First time building 2 storey home, is under construction (in Framing stage) in NSW. 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