Browse Forums Heating, Cooling & Insulation Re: continuous hot water with shower mixer 2Sep 29, 2019 12:25 am BBJ Hi, just choosing hot water system- do I need to consider anything about the system to accommodate 2 showers with 7.5 litre/min showers on mixer taps? Will using the mixer result in a low flow and loss of hot water? Will two showers running at the same time cause problems? Looking at thermann 26L 60 degrees- does this mean it's automatically set to 60 degrees when any tap is on full hot? Thank you!! I believe it's illegal to have a shower set at higher than 50degree. Or so I am told! Re: continuous hot water with shower mixer 3Sep 29, 2019 3:27 am BBJ Looking at thermann 26L 60 degrees- does this mean it's automatically set to 60 degrees when any tap is on full hot? Thank you!! Hi BBJ, If you want to run two showers at the same time, it more depends on how your hot water pipes are setup. Best setup I am told is to run a larger diameter 'manifold' from the HWS for a short distance, then run smaller individual pipes to each outlet...or at least to each area. But this is really only possible normally in a new build. Also with instant gas system of that size you will need at least a 3/4 inch gas pipe to the unit as they consume a high level of gas during operation (~200 mg/h I think). In terms of temps, if you install a 60 degree model legally the plumber has to also install tempering valves to the bathrooms to limit the temp to 50deg. With some models of the 50deg (eg Rinnai) you can bump up the unit temps to around 55 legally to allow for losses in the pipework so that technically it is still around 50 at the tap. Hope this helps. BTW I'm not a plumber, but have been building so researching this stuff a bit of late. --------------------------------------------------------------------- Check our Homeone build blog here Re: continuous hot water with shower mixer 4Sep 29, 2019 8:27 am also beware 26L does not mean taking 26L from 10c up to 60c they are rated at something stupid like 20 degree increase in temperature so it would take 26L from 10c to 30c so check how much flow with a 40c or 50c increase Re: continuous hot water with shower mixer 7Oct 02, 2019 12:07 pm BBJ Thanks for your replies everyone! Sounds like its more confusing than I thought LOL Hi BBJ, It is a bit more technical I guess than just picking a 'big' enough HWS unit. But from what I have been told and researched, your 26-27L rated instant gas units will be more than enough in terms of their ability to produce enough hot water for two 7.5l/m shower heads. The main issues might be:
Hope this helps? So basically installing just a large enough unit doesn't guarantee you can run both your showers with no noticeable pressure or hot water loss unfortunately. --------------------------------------------------------------------- Check our Homeone build blog here Re: continuous hot water with shower mixer 8Oct 02, 2019 12:12 pm BBJ aussieta now the specs make sense thank you! Looks like 25 degree rise at 26L and 40 degree rise is 16.5L- which is still two showers with 7.5L shower heads I'm guessing. The other things to consider is what size water pipes are going to feed in the 'cold' (to the HWS) and also feed out the 'hot' (from the HWS)? If they are around 15mm internal diameter, then because these supposedly have about a 16 l/m capacity throughput, there would be little benefit installing anything larger than a '16' rated instant HWS. With your 26-27 rated units they required 20mm (3/4 inch) inlet and outlets pretty much for their entire lengths. It's logical in that what is the point of being able to heat say 26 l/m with a 25deg temp increase, but the water can only be fed in or out at say 16 l/m? So many people mistakingly install these larger systems, whereas they would be better of going with a smaller unit. It's a bit like buying a ferrari to just put around the suburban streets to go to the local shops occasionally! --------------------------------------------------------------------- Check our Homeone build blog here Re: continuous hot water with shower mixer 9Oct 02, 2019 12:13 pm This plumber actually has some videos on the topic, so this might explain it better than a non-plumber like myself: https://www.youtube.com/watch?v=XpMjqAV-rIQ --------------------------------------------------------------------- Check our Homeone build blog here Re: continuous hot water with shower mixer 11Oct 02, 2019 3:36 pm darb74 This plumber actually has some videos on the topic, so this might explain it better than a non-plumber like myself: https://www.youtube.com/watch?v=XpMjqAV-rIQ Good link. Copper pipe sizes are nominal (internal diameters are smaller) and maximum flow velocities through pipes are regulated. A school kid who knows how to calculate a cylinder's internal volume and flow rate in metres per second would know that the plumbing shown in the video depicts incompetence. Sadly, the installation is still compliant. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. The time to heat is purely a function of the distance between the hws and the faucet. There are many options for hot water, you can also have a circulating circuit of hot… 1 8670 I want to build a decking to the drawn shape outlined in black. The problem is how close can I build to the gas hot water unit? Will I be able to build around it and be… 0 16174 DIY, Home Maintenance & Repair Hi, I've got a brand new (2nd hand) Bosch Hydropower 16H tankless hot water heater. Since it was installed I have noticed it leaks a lot. I took the cover off and it looks… 0 18093 |