[Anonymous]

We have a QL 20 water heater and recently both under engine and using shore-power the water has been dangerously hot- easily hot enough to make coffee or tea! I’ve tried adjusting the thermostat down, but that’s made no obvious difference, so i assume the thermostat is faulty.
Has anyone replaced a thermostat and if so how easy is it? Oh and where does one buy them?

John

[Anonymous]

I’m not sure which thermostat you mean.

Is it one of these http://www.cleghorn.co.uk/c-warm-heaters/c-warm-heater-accessories/cw268-thermostatic-blender-valve-15mm.htm?

If so, it should be fairly straightforward to replace.

If you haven’t got one of these fitted (they were not fitted as standard on earlier boats), then it is well worthwhile fitting one. Not only does it avoid scalding hot water from the taps, it also makes the hot water go further by mixing the (scalding) hot water direct from the calorifier with cold water before circulation to the taps.

[Anonymous]

Hi Roger,
No it’s not ‘one of those’. What you show is a thermostatic mixer, which controls the water temp leaving the heater (we don’t have one). My problem is with the thermostat which ‘inserts’ into the front of the water heater and controls the temp to which water is heated.

John

[Anonymous]

@Lazy Pelican wrote:

My problem is with the thermostat which ‘inserts’ into the front of the water heater and controls the temp to which water is heated.
John

Hi John

Understood re the thermostatic mixer. If you haven’t got one of these it is well worth fitting for the reasons outlined in my previous post.

Regarding the thermostat that ” ‘inserts’ into the front of the water heater ” is this the electric thermostat that limits the temperature when the water heater is using AC mains? This is the only thermostat I’m aware of that fits inside the calorifier. AFAIK there is no thermostat in the calorifier that limits the temperature when using the engine. There is, of course, a thermostat in the engine itself that limits the overall temperature of the engine and coolant but this allows the water to reach something like 85C, pretty hot for domestic hot water (hence the benefits of the thermostatic mixer!).

If it is the electric thermostat that is causing the problems, this should be easy to remove and replace, assuming QL/Volvo can supply a suitable replacement. There should be 2 wires to disconnect/reconnect.

Good luck.

Roger

[Anonymous]

Hi Roger,

I’ve looked at the thermostat again and think it’s working ok, so you’re suggestion of a mixer on the outlet is probably the answer.

Many thanks,
John

[Anonymous]

Whilst I understand the concern of having very hot water available at the taps, so long as everyone on board is aware of the danger and capable of using the mixer taps, the hotter the water in the calorifier, the longer it will last before you need to connect to shore power or fire up the engine.
We thought about fitting a mixer valve, but in the end convinced ourselves that the capability to store the hotter water was a benefit worth having.

[Anonymous]

The mixer valve mixes the water as it exits the calorifier. When a mixer is fitted the water is still stored in the calorifier at the highest temperature. It is mixed with cold water on it’s way to the taps.

You will find a mixer valve actually makes the hot water go further/last longer as not so much of the hot water is wasted while the temperature at the tap is adjusted to suit!

[Anonymous]

Thanks for that Roger, I now understand why the mixer valve is a good idea.

[Anonymous]

Hi Roger,

I have the thermostatic mixer CW268.
It requires both Hot and Cold feeds. I’ve 2 cold water water tanks so 2 feeds into the water heater- have you connected both your c/w tanks to the mixer and if so how?
Also does the standard 15mm Whale PVC pipe work with the mixer compression fitting?

Thanks,
John

[Anonymous]

Hi John

I fitted the mixer close to the calorifier. I took a T off the cold feed to the calorifier and routed the calorifier hot output to the valve and the valve output to the taps.

It can be a bit of a fiddle depending how much room you’ve got to work in. I’ve attached a photo of my finished installation. Not the neatest, but it works fine!

The push fit plastic tube and connectors work well; however, the connection from the calorifier to the valve should, ideally, be copper as it is taking the full temperature of the hot water.

[Anonymous]

Thanks Roger – very helpfull.
Is your c/w supply to the thermo valve taken from both your c/w tanks or just from one?
If from one how does the systen work when that tank is empty?
If from two how did you achieve this?

Thanks again for you help,
John

[Anonymous]

Hi John

Do you not have a changeover valve somewhere so you can choose which tank is feeding the c/w system? The valve on Playtime is in the cupboard behind the shower, where the water pump, shower drain pump and filter are located. The output pipes from the 2 tanks feed through to a 2 way valve – lever vertical is front tank, horizontal is rear tank? The out put from the valve goes direct to the c/w pump.

Surely you have something similar, otherwise how do you change from one tank to the other?

[Anonymous]

Hi Roger,

What you’ve done looks great and I’m thinking of doing the same. My only concern is whether the (metal) compression fittings on the CW268 will work on the Whale plastic piping that is designed for push connections. Can you clarify this for me?

Riyad Abu-Laban
s/v Battuta
B31: Vancouver, Canada

[Anonymous]

@Battuta wrote:

My only concern is whether the (metal) compression fittings on the CW268 will work on the Whale plastic piping that is designed for push connections. Can you clarify this for me?

There are inserts available for use with plastic pipe in compression fittings. You insert one inside the plastic pipe to stop it being crushed in the fitting. I used them on the 2 plastic pipes visible in the photo above. I’m not sure what they are called but if you explain the requirement to your plumber’s merchant or chandler they should be able to find the necessary.

Good luck.

[Anonymous]

Hi, my problem is the heat of the water from the engine to the calorifier causes the trip switch on the 2nd immersion heater to trip, which would happen if the thermostat on the first immersion heater did not cut off the power at the required temperature when connected to the mains supply. So how do i prevent the trip switch from opperating when under engine alone?

Ed Holmes Storm Dragon 1997 vintage boat

[Author]

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