Electric tap/shower

[CatherineS]

Refitting an old boat out currently to live aboard with family (2 adults 3 children) so fairly instant hot water necessary, we plan to stay in marinas 95% of the time, maybe a day or two cruising at a time in the summer but I imagine we’ll have a hook up for the majority of our days, so, is an electric hot tap for kitchen & electric shower do able? Haven’t seen the taps fitted in any boats we’ve come across so wondered if anyone has one & could comment or is it just not a good idea. Any advice appreciated. Tia. 

[Tony Brooks]

 

If you have a water cooled engine, I would have thought a calorifier, so the engine will heat the water (free) whilst cruising, and a mains immersion heater to heat it when you are hooked up.

 

You can have whatever mains electrical equipment you like as long as it's current demand is within what the shoreline can supply, many are less than 13 amps. However, trying to do it from the batteries via an inverter is likely to end in tears

[CatherineS]

Thanks for your reply, I’m pretty sure there’s a calorifier, there’s also an very very old rinnai heater in the kitchen, wondering if it’s better to just replace this so I don’t have to rely on electric but not sure the best way to go. 

[Tony Brooks]

5 minutes ago, CatherineS said:

Thanks for your reply, I’m pretty sure there’s a calorifier, there’s also an very very old rinnai heater in the kitchen, wondering if it’s better to just replace this so I don’t have to rely on electric but not sure the best way to go. 

 

An instant gas water heater (Rinnai) plus a calorifier suitably valved so both can't supply the taps at the same time some consider the optimum system, but new instant gas water heaters for boats are a minefield nowadays.

 

 

Edited to add: You may find an immersion heater when on a shoreline is cheaper to run than a bottle gas water heater.

Edited February 9 by Tony Brooks

[Tracy D'arth]

An electric shower of less than 8kW will be considered inadequate.  Certainly in winter when the water is colder to start with.

8kW on the mains is 32 Amps. Most marinas will supply at most 16 Amps, some even less, so that will not work.

To use the batteries to heat water is a no-no, the current required is at least 20 times what it would be on the mains.

The best way if you have a shore line is an immersion heater in the calorifier.

Gas is getting very expensive in bottles.

When out, the engine will heat the calorifier, so if you move a bit every day to charge batteries you will have hot water.

 

Edited February 9 by Tracy D'arth

[David Mack]

3 minutes ago, Tracy D'arth said:

An electric shower of less than 8kW will be considered inadequate.  8kW on the mains is 32 Amps. Most marinas supply at most 16 Amps so that will not work.

Domestic instantaneous electric showers are 8kW upwards. One that size would be regarded as a basic model in a house, and 11-12kW models are becoming more common. No way you could do that on a boat.

The equivalent heater for a hot tap, as found in factory washrooms and the like away from a piped hot water supply, is typically 3kW, so you could do that in a boat on a shore line, but I can't see the point if you have other sources of hot water anyway.

[CatherineS]

8 minutes ago, Tracy D'arth said:

An electric shower of less than 8kW will be considered inadequate.  Certainly in winter when the water is colder to start with.

8kW on the mains is 32 Amps. Most marinas will supply at most 16 Amps, some even less, so that will not work.

To use the batteries to heat water is a no-no, the current required is at least 20 times what it would be on the mains.

The best way if you have a shore line is an immersion heater in the calorifier.

Gas is getting very expensive in bottles.

When out, the engine will heat the calorifier, so if you move a bit every day to charge batteries you will have hot water.

 

Thanks for this, really helpful! We are new to boat life don’t want to make too many mistakes, appreciate your comment. 
 

1 minute ago, David Mack said:

Domestic instantaneous electric showers are 8kW upwards. One that size would be regarded as a basic model in a house, and 11-12kW models are becoming more common. No way you could do that on a boat.

The equivalent heater for a hot tap, as found in factory washrooms and the like away from a piped hot water supply, is typically 3kW, so you could do that in a boat on a shore line, but I can't see the point if you have other sources of hot water anyway.

Yes I agree it only made sense to have electric tap & shower if no other means were needed but makes sense to go a different route. Thanks for your advice. 

[blackrose]

53 minutes ago, CatherineS said:

Thanks for your reply, I’m pretty sure there’s a calorifier, there’s also an very very old rinnai heater in the kitchen, wondering if it’s better to just replace this so I don’t have to rely on electric but not sure the best way to go. 

 

On boats it's not either/or it's both. Sometimes you'll want to use the mains immersion from shore power and sometimes you'll want to use the gas water heater. There must be a valve with a lever somewhere allowing you to select the hot water supply.

 

If you do have a mains immersion heater in your calorifier consider fitting a timer as having it come on a couple of times per day will be cheaper than just leaving it on 24/7.

Edited February 9 by blackrose

[Stroudwater1]

I would be pretty sure that the Rinnai heater you have will be fine. Many boats have them and the joy of hot water instantly is especially important with three children. You won’t get hot water as fast all the time in any other way. 
 

Old it maybe but they are fairly bombproof. If it doesn’t work then contact @Paloma Bob who  will service them. There are a number of people that will remove it and refit once serviced. It may just need the pilot light cleaning? 
 

By all means have other ways of heating but your plans / needs may change. You may regret getting rid of it. 

[rusty69]

I would agree with everything that had already been said above. We have both an instantaneous gas water heater and a calorifier on our boat, suitably valved such that we can switch between the two. The calorifier has a thermostatic valve on the output such that the temperature can be set so not to be too hot. 

 

The use of a gas water heater will consume quite a bit of gas, so make sure your bottles are adequately sized, and ideally available at the marina at short notice if you don't have a spare. Similarly, the calorifier will need to be big enough for everyone onboard, or showers staggered so that water has time to heat up again. 

 

We have both a paloma and a rinnai (on separate boats) , and I much prefer the paloma. Be aware that as the temperature in the winter drops, you may need to increase the temperature selector on the heater, which in turn reduces the flow rate. Showers in winter with gas water heaters are not as good as those using the calorifier. 

Edited February 10 by rusty69

[Lady M]

To minimise gas use, don't leave the pilot alight on the gas water heater. 

[blackrose]

54 minutes ago, rusty69 said:

Showers in winter with gas water heaters are not as good as those using the calorifier. 

 

Yes I ended up fitting a higher pressure domestic water pump to fix this issue with my Morco instant gas water heater.

[cheesegas]

1 minute ago, blackrose said:

 

Yes I ended up fitting a higher pressure domestic water pump to fix this issue with my Morco instant gas water heater.

Usually the problem is that the gas water heater can't put enough heat into the water in winter as the supply water is a lot colder. They have a fixed temperature rise so if you increase the flow rate, you just end up with a higher pressure but colder shower! Sounds like you had a different problem though.

 

Also worth noting there are currently no room sealed propane instant water heaters on the market which can run off 12v - every single one will need an inverter. As the electricity runs the control board, ignition and flue fan it can't be easily converted. If you have a Rinnai etc, it's best to get it serviced or repaired rather than replace!

[blackrose]

4 hours ago, cheesegas said:

Usually the problem is that the gas water heater can't put enough heat into the water in winter as the supply water is a lot colder. They have a fixed temperature rise so if you increase the flow rate, you just end up with a higher pressure but colder shower! Sounds like you had a different problem though.

 

I'm not sure. All I know is that the new pump had the same flow rate specification as the old pump but a higher cut out pressure (40 psi instead of 25psi). 

 

The problem I had was that the Morco would cycle from hot to cold with the original pump, whether I was using the shower or just the kitchen sink hot tap.

 

Some here said fitting a higher pressure pump with the same flow rate wouldn't work because it was the flow rate that needed to be increased not the pressure, but fortunately they were wrong because it worked a treat and the shower and tap water stays hot and doesn't cycle between hot & cold.

Edited February 10 by blackrose

[Alan de Enfield]

We fitted an 'electric hot water tap' into the stable block (the Horses like to give their feet a wash before going to bed, and the 'girls' like to wash their hands before eating their butties).

 

It works really well but the volume of water is quite low, the higher the temperature setting the lower the flow rate, as it is an 'instantaneous system' that the water is heated as it passes the element, the slower it passes the hotter it gets.

 

It can be used as both a hot water and cold water tap.

 

It is pefectly adequate for hand washing, or maybe doing your 'smalls' in the sink. It would not work as a shower.

 

Simply remove the existing tap replace with the new onw, connect up the water, plug it into a 230v supply and you have 'hot water on tap'.

 

The one we bought was similar to this :

 

3000W Electric Heating Tap Kitchen Bathroom Fast Instant Hot Water Heater Faucet | eBay

 

Power	3000w, 220v
Working Pressure	0.03-0.5mpa.
Water Temp	30-60c
Waterproof	Ipx4
100% Water Electric Separation
Abs Mouth Pipe 360 Degree Rotation

 

 

 

 

14 hours ago, CatherineS said:

we plan to stay in marinas 95% of the time, maybe a day or two cruising at a time in the summer but I imagine we’ll have a hook up for the majority of our days, so, is an electric hot tap for kitchen & electric shower do able? Haven’t seen the taps fitted in any boats we’ve come across so wondered if anyone has one & could comment or is it just not a good idea.

 

It would certainly work for you as a 'kitchen' tap when you were in the marina (95% of the time), when out cruising it would just be a 'cold tap' .

Edited February 10 by Alan de Enfield

[blackrose]

I can't see the point of the 3000W hot tap if you have say a 1.25kW immersion heater fitted? You'll probably find the hot tap trips the boat's breaker or the breaker on the mains bollard half the time you use it if any other high power mains appliances happen to be on at the same time. The usual 16 amp shore power supply is only about 3750W isn't it?

Edited February 10 by blackrose

[cheesegas]

45 minutes ago, blackrose said:

The usual 16 amp shore power supply is only about 3750W isn't it?

In theory yes, but most marinas have severely undersized cabling leading to excessive voltage drop, especially if you're at the end of a pontoon. Usually made worse by a 20m shore power lead made from crap 1.5mm blue arctic... You may only get about 3000w before the the breaker trips. The last time I stayed in a marina I routinely saw 200v AC on the input of my Multiplus when charging batteries, pulling only 1500w from the shore. It would have definitely been lower if more boats on the pontoon were inhabited and I was trying to pull more!

 

And yep, I agree, a 3000w appliance on a 16a shore power connection is a bad idea, you'd need to be careful not to run it with the immersion or anything else even slightly high power switched on. Some of the hot taps I've seen have a small holding tank under the counter which is kept warm all the time, controlled by a thermostat - if this tap is similar, you wouldn't even know when it's pulling 3kw!

[ditchcrawler]

I read of someone trying it with a 3000VA inverter, it didn't end well

[Tracy D'arth]

4 hours ago, ditchcrawler said:

I read of someone trying it with a 3000VA inverter, it didn't end well

Trying to get 260A plus inverter losses out of batteries is not a good idea..............

 

I have found practically no marinas where you got the full 240V @13A supply to a boat.  Some are only 5A

Best I found was a dairy farm where the electrics were straight off the overhead into their own transformer. You could see 256V when they were not milking cows or cooling the tanks.

[IanD]

57 minutes ago, Tracy D'arth said:

Trying to get 260A plus inverter losses out of batteries is not a good idea..............

 

I have found practically no marinas where you got the full 240V @13A supply to a boat.  Some are only 5A

Best I found was a dairy farm where the electrics were straight off the overhead into their own transformer. You could see 256V when they were not milking cows or cooling the tanks.

The marina I'm at (Uplands) will happily supply 16A/230V (3.7kW) for several hours continuously...

 

(this is after the isolation transformer which has a slight step-up, so shoreline input is 230V/16A when charger sees 250V/15A)

Edited February 10 by IanD

[cheesegas]

Compare that to a certain marina on the GU where I left my boat for a couple months while I was away for work...not connected to shore power all the time, mind!

[LadyG]

On 09/02/2024 at 19:17, CatherineS said:

Thanks for your reply, I’m pretty sure there’s a calorifier, there’s also an very very old rinnai heater in the kitchen, wondering if it’s better to just replace this so I don’t have to rely on electric but not sure the best way to go. 

There most likely be a calorific, but less likely that it has an immersion heating element fitted, I would certainly make sure you build in redundancy with such a busy boat, and use marina facilties as much as possible. Five people showering in the morning would cause a lot of hassle and likely create condensation. Either way, a fan would be required, maybe an opening porthole or window..

I have a boat with a solid fuel stove with back boiler, gravity feeding, via fat copper pipes, to the calorifier., this is simple and keeps the boat warm and dry.

The Webasto gives me hot water for calorifier and for the radiators when selected.

My boat shower takes water from the calorific, though the water temperature is not adjustable like a domestic electric shower, which could be inconvenient.

[IanD]

53 minutes ago, LadyG said:

There most likely be a calorific, but less likely that it has an immersion heating element fitted, I would certainly make sure you build in redundancy with such a busy boat, and use marina facilties as much as possible. Five people showering in the morning would cause a lot of hassle and likely create condensation. Either way, a fan would be required, maybe an opening porthole or window..

I have a boat with a solid fuel stove with back boiler, gravity feeding, via fat copper pipes, to the calorifier., this is simple and keeps the boat warm and dry.

The Webasto gives me hot water for calorifier and for the radiators when selected.

My boat shower takes water from the calorific, though the water temperature is not adjustable like a domestic electric shower, which could be inconvenient.

Why not fit your shower with a thermostatic mixer fitting to take in hot water from the calorifier and cold from the tank and provide a shower at the right (and adjustable) temperature?

[rusty69]

......or fit your calorfiier with a thermostatic valve that controls the temperature to all taps and shower.

[magnetman]

I had an electric tap once. It was rubbish. 

 

Electric chairs are much better. 

 

Its just easier to get unwanted guests to wash their hands.