Adding hot water to one sink

[Flyingspanner]

We have a Finnmaster T8 day boat that does not have hot water - up to now we have never slept on the boat but next year we will stay on the boat for a night or two - the only thing we don’t have is any hot water without us either boiling a electric kettle or using the diesel hob to boil a kettle - It would be nice while we are hooked up to electric in the marina to have one of the sinks with ‘hot ish’ water - I don’t want to go the full calorifier cylinder / pipework / valve installation but have seen these under cabinet electric water heaters like this one - do you think it would work on a boat to a single tap ?

 

[jfm]

That looks like it will work.
Consider setting it to the highest temperature, because that increases its effective volume. 5 litres of water at 60 degrees is like 6 litres at 50 degrees, and so on. Because you will always be blending it with cold, and you will use less volume of hot in the blend, the hotter the hot water is.
OTOH, if you have young children on board you might want a lower temperature.

 

[James jameson]

Watch you need a vented tap or an additional kit for this type of heaters. Don’t just install the heater and pipe direct to a tap

 

[Davy_S]

I have the same model but use it for a domestic supply, it works very well, it heats up in 9 minutes and is VERY hot if you turn up the heat setting, as it is unvented you really could use one of these, for some reason the link did not work, but its a 2 litre expansion vessel cost around £26.

 

[Flyingspanner]

Watch you need a vented tap or an additional kit for this type of heaters. Don’t just install the heater and pipe direct to a tap

Thanks - I will keep looking at them and find some instructions for installing one

 

[Flyingspanner]

I have the same model but use it for a domestic supply, it works very well, it heats up in 9 minutes and is VERY hot if you turn up the heat setting, as it is unvented you really could use one of these, for some reason the link did not work, but its a 2 litre expansion vessel cost

 

[Flyingspanner]

Thanks - will look a bit deeper - some of the units I have looked at say no additional expansion vessel is required as the unit has a pressure relief valve and drain line ?

 

[Davy_S]

Thanks - will look a bit deeper - some of the units I have looked at say no additional expansion vessel is required as the unit has a pressure relief valve and drain line ?

The pressure relief valve is to do with 6 bar mains feed, mine is fitted with a test valve as well, to be honest i fit most things myself, but i was not confident about the need for a pressure vessel, so i got a plumbing mate who i trust, to advise me, he said it was safer to fit the pressure vessel, so it seemed safer rather than blow up the cupboard where it is fitted the choice is yours of course, its a very good piece of kit, there is also an anode inside it that may need a yearly check.

 

[Seastoke]

Have a look at the dexpro instant under sink 3.5 kw it would run off a 16amp supply and is not bulky like the storage unit. Just another option.

 

[Plum]

We have a Finnmaster T8 day boat that does not have hot water - up to now we have never slept on the boat but next year we will stay on the boat for a night or two - the only thing we don’t have is any hot water without us either boiling a electric kettle or using the diesel hob to boil a kettle - It would be nice while we are hooked up to electric in the marina to have one of the sinks with ‘hot ish’ water - I don’t want to go the full calorifier cylinder / pipework / valve installation but have seen these under cabinet electric water heaters like this one - do you think it would work on a boat to a single tap ?

I have a calorifier but the point JFM makes about heating to a higher temperature to get a bigger volume when mixed with cold is a good one and that is what I do with my calorifier. However for safety, I fitted a thermostatic mixer valve so no matter what hot water temperature comes out of the heater you can pre-set your prefered temperature at the tap. https://www.screwfix.com/p/pegler-peg402-tmv-15mm/96288

 

[Flyingspanner]

Have a look at the dexpro instant under sink 3.5 kw it would run off a 16amp supply and is not bulky like the storage unit. Just another option.

Great that looks a good unit - will draw a boy 14.5 Amps so just on the limit

 

[Flyingspanner]

I have a calorifier but the point JFM makes about heating to a higher temperature to get a bigger volume when mixed with cold is a good one and that is what I do with my calorifier. However for safety, I fitted a thermostatic mixer valve so no matter what hot water temperature comes out of the heater you can pre-set your prefered temperature at the tap. https://www.screwfix.com/p/pegler-peg402-tmv-15mm/96288

Yes JFM’s point is definitely valid - I have just realised I will need a different tap as mine only has 1 feed (cold) -

 

[Seastoke]

Yes JFM’s point is definitely valid - I have just realised I will need a different tap as mine only has 1 feed (cold) -

On the instant you can set temp