Bosch Hot Water & Heating Electronic Highflow 21e Questions & Answers (page 3 of 3)

You can fit a remote temperature controller which allow you to adjust the water temperature
Check withyour plumber or your owners manual
Cheers

Hi, I had a similar problem. Since these units work on a “pressure drop” to control the temperature rise it’s important to ensure FULL FLOW is available to the unit,don’t be fooled by high pressure as that will change with demand, the pressure drop has to occur in the unit. Check your factory fitted strainer first for debris. I checked mine and found what looked like some scale from the copper pipes - cleaned it but no luck. I conducted some time trials from different outlets as the hot water was alway inconsistent - on / off. Whilst during these trials l could hear a high pitch noise from my inlet piping - not normal, I tried to isolate by the supply tap but unsuccessful and had to isolate the house. On removing the pipe I discovered a lot of foreign material plugging the flow. The material turned out to be the taps washer which had disintegrated and was causing a pressure drop at the fouled point and not in the unit, the unit saw very little pressure drop due to the restriction. Simple fix - reseat the tap and install new washer -$1.50 - flush all the line to the strainer and now consistent adjustable hot water

Hi Aron
If this has just started after a time of reliable operation then first I suspect it is the water flow sensor, I can only suggest you turn off the power and check and clean all the push on connections, if that doesn't work you will need to get a service person. Check my previous posts for more info.
Cheers

Thank you for the answer. Unfortunately this is a brand new unit. Any other suggestions would be appreciated

Aaron

Thank you for the answer. Unfortunately this is a brand new unit. Any other suggestions would be appreciated

Aaron

Youve run out of gas fella

No. Sounds like you have a gas leak . Call a plumber as soon as possible to have it checked out . Safety first . You can rub soapy water on the connection points of the gas pipe . If it begins to bubble you have found the leak .

I would call a gasfitter. If you call Bosch they will direct you to approved repairers in your local area. We recently had a problem with 21e sounds similar to your problem. We needed to reset system to get it to work. Gasfitter found faulty part. $205 including labour. I cant remember the name of the part.

Hi David, We have just had ours not work and this morning had my partner outside at the unit while I was inside working the tap. He switched both the gas and the power off, I ran the tap and he switched it all on again, banged the unit with his hand LOL, and now it is working, good luck! (ours is only 3 months old :\ )

Hi we just ran out of gas this morning and switched our bottle over to new one manually- when it came to using the hot water tonight we couldn't get it to work - after reading the previous reply to David I turned off my gas bottle and turned power switch to hot water heater off- then turned gas back on and heater power switch also back on it worked straight away so thankyou for your last comments- we didn't even have to bang it -ha

If it is only in the shower you have a restricted shower. There is not enough flow through unit to maintain combustion.

I use a 9L standard shower head and it works fine with the flow restrictor intact. Any less than that and I don't think the hot water flow would be enough to start the flow ignition in the hws unit.

We have learnt to turn on the bottom shower and the water runs hot, turn on the top shower and turn off the bottom shower...different shore heads...so I might buy the same one as downstairs...thanks for the feed back

Does anybody have any ideas to help please?

I had a similar problem and it seems that the water flow rate should be 9 litres per minute.
I removed the water saving device from the shower head and the problem has been totally solved.
There may also be a device in the flexible hose if fitted.
Paddy

Thank you for your anser Paddy. Something we will definitely check.

I am not a plumber or gas fitter and mine are Natural Gas, so the only thing I can suggest is turn it off at the power point for about 5 minutes and then back on.
Good Luck

Thank you both. Extremely helpful. I will ring bosch :)

Hey there,

I am not a Plumber (second person who thought I am) and would not know what the fix is but if it were my unit, 10 years of service is fab in my opinion, I would just replace it with a highflow 26e if the remote controller is the same :)

Thank you for your answer house husband. That's what I thought too. By the time I found a new replacement ( a Rinnai this time ) I reduced the temperature from 50 to 47 degrees and it works perfectly - maybe it was overheating at 50 degrees. The new one sits in the garage until the old one konks out completely. 007

Cyclops - I am sorry but I cannot help you with that problem, I can say that my system is only about 1 year old and since your post, my hot water is also going cold unless I have it on full stream water. So if you happen to find the solution I would also like to know why this happens. Many thanks

Hi Cyclops - I too have no answers for you, our system is going on 1 year old now and we constantly had cold water issues and I was told that you had to have a certain number of literes per second going through the tap and the only way to regulate my water was to turn the tap fully on. I agree it is a waste of water but if you want a nice shower that is all you can do. Personally I wish I had all this information before we got this system as I am very unhappy with it.

do you need the flow rate adjusted maybe? if not then have your unit checked by a bosch service plumber for debree or spider web in the pilot light pipe, can cause the flame to be off target.....

If Bosch are claiming and min 2 1/2 litres per minute that doesn't sound right. In my experience you want a flow pressure at least 9 l/min from any outlet.

Thanks everyone, after I put these questions I bit the bullet and removed the restrictor washer and the problem's solved. Lukewarm showers down to 37 degrees (in the hot weather) not previously experienced. Lee.

Sorry I can't be of any help whatsoever on this.

Yep - pull out the flow restrictor in your shower and it'll work fine. It's not a Bosch issue, it's based on the flow pressure and every instantaneous has this issue. You can buy flow restrictors at 6 l/min, 9 l/min or 12 l/min at most plumbing suppliers. Maybe try the 9 and then the 12 if you want to be real conscience of your water usage.

See my answer below, pity about extra water usage but it won't be too much of a problem because we only take short showers. Thanks Saint Just.