Instant handwashers.

[Jimk]

& D i m ?

[T i m]

Years ago I nearly commissioned a conventional stored HW / CH system here but at the last knocking replaced the BF boiler with a BF multipoint water heater.

The only issue because of that path is that the hot supply from MPWH to downstairs bathroom basin / bath is in 22mm copper and so has a greater volume than had it just been 15mm.

This means that if you add the warm up time of the heater you are looking at around 30 seconds from cold to starting to get reasonably hot water though (after that it's continuous of course).

Not an issue if running a bath, a bit of an issue (time, water usage etc [1]) if running a basin of hot washing water but quite an issue if repeatedly wanting to wash your hands of Covid-19 in reasonably hot water and reasonably quickly.

A mate has just had a little (size and power consumption) Triton T30i instant water heater that he says provides suitably hot water in about

5-6 seconds so that would be a vast improvement. I also have very good access to a mains water pipe and utility room ring main.

I also have reasonable access to the cable that feeds the Triton T80 electric shower but would prefer not to tap into that, even if it was advisable (what about the unlikely event of running the shower and hand washer at the same time (as they are in the same room etc)).

But the thing that I haven't decided is if it would be worth going for one of the automatic, instant hand washing units and the question is really how practical are they in use?

eg, If you have to wave your hand in front of them, do you get enough water, long enough to wash your hands 'properly' (so 20+ seconds of 'hot') and how likely is it they would trigger unnecessarily, like if going to the std basin taps or the bathroom cabinet past it on the back wall (said water heater would be on the lhs wall).

The storage type water heaters (under / over sink), whilst allowing the use of the std hot tap, do have to store the hot water (more losses?) and the hot becomes diluted quickly as the cold comes in (a problem if wanting to wash / rinse several things under hot running water), potentially requiring a bigger unit to get the volume of hot water required before temperature recovery).

So I'm guessing the most efficient / tidy solution could be an undersink instant water heater but they are typically over 3kW so would need serious considerations re the feed wiring.

So it think the best *compromise* would be the small oversink instant, just if to go manual or automatic?

FWIW, no one in this house cares what it would 'look like' in our bathroom and I'm guessing that it might not get as much use once /(if) things go back to normal (but the nozzle can be swiveled out the way etc). That said, it could be better than drawing hot though the MPWH for night time teeth cleaning etc?

Cheers, T i m

[1] Not on a water meter but as we have our own feed off the main (the other houses in the terrace are still on the communal supply), we could go on one if it was deemed an advantage (small 3 bed cottage, 2 occupants, rare car washing or hose use etc).

[Chris Green]

I've installed two of these in my house (not at the same time, the first worked so well I installed another) :-

Only 1.5kW so can simply plug in if you want, or use a dedicated immersion heater style circuit.

They don't need expansion chambers or anything silly unless your mains water pressure is unusually high, or you can do what I have done and run them off the 'tank in the loft', flow rate downstairs is perfectly OK doing this.

[T i m]

Ok, that's handy.

I don't believe it is but then I've never measured it? How does one?

No tanks in the loft.

Understood.

What would be really good is if you could feed it off the MPWH, as that way you could run it continuously and remove the 30 delay issue.

I know they state 'cold water feed' and it may well depend how hot your 'cold water' was. ;-)

Alternatively, if I could fit a pedestal lever tap onto the work surface beside the ceramic basin I could have this for the 'quick' hand washes and the std hot tap for everything else?

How much actual hot water would you think you get from your ~6l Chris?

Cheers, T i m

[Dave Liquorice]

Unless you've been out near other "dirty" humans why do you need to wash your hands any more than normal when at home inside your "clean " bubble?

Certainly first thing when you come in, and not touching door handles etc as you enter. Unpack anything, dispose of any outer wrappers and wash hands again but after that?

[Jim GM4DHJ ...]

indeed

[Robin]

and also why hot water when cold is just as effective for getting rid of pathogens?

[Chris Green]

One of mine *is* actually on the hot water feed as there wasn't low pressure (i.e. not mains) water available at the kitchen sink.

Certainly enough to wash hands, the kitchen one is actually set a bit too hot to wash hands in hot only. Using them to put water in a bucket one can certainly get a bucket of hot water.

[T i m]

Well, that's part of the ting, this 'delay' before the hot water comes though has always been a minor issue but more so now there are only two of us in the building and the current situation.

Can't do that with these doors but we might use a sleeve instead, unless I only have a T-Shirt on (and trousers etc). ;-)

Daughter has just arrived arrive with some shopping. What we typically do is leave anything we don't need to put in the fridge or freezer in it's bags out of the way for as long as we don't need it.

Anything that needs to go in the fridge or freezer I'll wash down with soapy hands and rinse if sealed.

Fruit / veg I can also wash with soapy water and rinse / dry with paper towels.

As you say, open cereal and tip into pre opened containers, wash hands, put lids on containers and put away.

Taking post off postman / courier, picking up one of the bags the shopping is still in, going to the car and back.

But yes, you are right, as long as you keep track of *everything* and can process all your shopping at once, then you should be ok. I'd try to improve that 'should be' the best I can and so that means regular hand washing in between.

Plus I still have the issue of the 30 seconds wait every time I wash my hands in between, like if I'm going to make some food or after going to the toilet etc.

It's like I / we have a 'Covid free' timer running and as soon as we get there (say 5 days) without showing any signs we feel happy. Get some mail, have someone drop something off, have to go out to get meds / whatever and whilst we are as careful as we can be, we assume the clock is back to zero and we have to start again.

That's what the 'Stay indoors' thing is all about but I'm guessing all the people dying in care homes have been doing that?

Cheers, T i m

[T i m]

As in it isn't, it's the soap. ;-)

I wasn't sure if that (cold water as good as hot) was the case when I posted but it appears it is, however, it's still more comfortable using hotish water and possibly easier to a good lava off bar soap as it 'melt's easier?

Cheers, T i m

[T i m]

Cool. And is the input water temperature ever such that the unit doesn't need to do anything Chris?

OK, and real-world recovery times?

Ok. I was thinking about that if you wanted to do a running water hand wash (to wash dirt / germs 'away') as opposed to washing them in some standing hot water (shower V bath sorta thing)?

Cool, that's a good example. In this case you couldn't get a bucket under the tap but that gives me an idea that you get a fair quantity of useable water. I'll have a measure up and see what sort of space I have under the sink.

I notice they also do 'Above sink' units and whilst it would probably be easier to get one sited, it would mean a longer run to the tap and so not addressing the issue quite so well.

Cheers, T i m

[Bob Eager]

Lava would definitely kill the virus!

[Tim Streater]

Yes, two screwups in half a sentence.

lava -> lather melt -> dissolve

[T i m]

Ok, don't work yourself up into a lather over that. ;-)

Cheers, T i m

[T i m]

Three left brained observations in one post!

'Screwups'! Bwhahahaha!

"melt: make or become liquefied by heat." ...

and given it's the heat component of the process I was referring to, not the dissolving by water ...

Thanks for playing, you melt!

Cheers, T i m

[Bob Eager]

I just thought it was rather funny!

[T i m]

Yeah, it was. The problem I have with my mild dyslexia is that I often don't see a word being spelt incorrectly, even though I'm fully aware there are several spellings of the same sounding word (with different meanings). What / watt, which / witch, stair / stare, too / too / to, bow / bough, deer / dear, gate / gait, hare / hair, inn / in and very similar sounding words (and often pronounced identically, especially in Norf Lundin) like lava / lather and Streater / Tw*t. ;-)

I was trying to consider the resultant of combining our MPWH and the local stored 6l of 'hot' water.

So, say you open the tap to a point where the MPWH would kick in and on the first run of the day.

You would have a short period of time as clears the plug of cold (or would it actually be warmed by conduction from the hot tank so 'warm') water between the tank and the outside of the tap. Then you get the full temp water off the top of the tank. That would start to run cooler as the cold water in the length of 22mm pipe between the MPWH and the tank starts to 'dilute' the temperature. After the tap has been open about 30 seconds, the hot water would have been coming though at the tap but now there will be a delay as it infuses with the cold water in the tank while the temperature slowly builds back up to the temperature of the output of the MPWH (for that flow rate).

Turn the tap off now and it may be that the water in the tank is now lower than that coming out of the MPWH and so if left it will slowly cool back down till the tank stat kicks in and maintains that temperature.

If we only use the tap for less than 30 seconds (and that sounds likely as you would have hot water from the off), the hot from the MPWH wouldn't reach the tank and so it would have to heat back up electrically.

However, you would get the (near) instant hot water for semi-regular hand washing and you could run the system continuously if you needed (like rinsing loads of stuff under hot water).

I wonder if the instant water heaters would equally tolerate a hot feed as that really would tick all the boxes?

Assuming the heat exchanger can tolerate the temperature of the hot water (and may see such inside anyway when you turn the tap off, trapping the heated water inside) then it should only kick in [1] for the first 30 seconds (and worst case at that) and only heating as required to attain the chosen output temperature?

Hmmmm ...

Cheers, T i m

[1] I wonder how well it would modulate the already hot water? Obviously it can't make it colder.

[Chris Green]

Presumably yes, but how would I know? :-)

The temperature is adjustable so you can turn it down so that it's a comfortable 'hot' hand wash.

[T i m]

<snip>

Isn't there a 'heating' light on the front or anything?

But then not as much thermal capacity I'm guessing.

Cheers, T i m

[Chris Green]

Yes, there is, but I've never bothered checking to see if it goes out when one runs a lot of water through. It would also require that the 'tank' thermostat is set higher than the under-sink heater's.

Of course.