Author Topic: Shower is too hot until the pump runs... accumulator tank time? (Read 2755 times)

MagicalArmchair · « **on:** April 13 2023, 19:49 »

With four children, showering them on board is much easier than marching down to a marina ablutions block - and besides, we'd prefer to stay out of marinas.

We have the standard, factory fit water system which does not include an accumulator tank.

When we start the shower running, it goes red hot until the fresh water pump starts running, once the pump is running the temperature evens out. This wastes water and precious HOT water at that (at a premium with effectively six to shower!!). Would adding an accumulator tank in the cold run just after the pump address this issue? What have others done?

Yngmar · « **Reply #1 on:** April 13 2023, 19:58 »

We've always had an accumulator tank, and despite them constantly dying and/or needing pumping up, we've kept one, as they're quite useful in reducing pump cycling.

We also _had_ to add a thermostatic mixing valve at the calorifier, as our engine produces 95°C hot water, which destroys the Whale QuickFit plumbing connectors - they're only rated for 60°C. Took a few leaks to figure that one out. It's now mixed down to about 50 degree before entering the red plastic pipes.

Finally, we've got a thermostatic shower head - that was already on the boat. Useful as the calorifier temperature varies and saves water as none is wasted while the user adjusts temperature manually.

We still prefer the marina shower, because someone else is cleaning it! But we don't have to manage miniature crew.

tiger79 · « **Reply #2 on:** April 13 2023, 20:26 »

A thermostatic mixing valve on the calorifier is essential. An accumulator isn't necessarily essential - modern pumps don't need one.

MagicalArmchair · « **Reply #3 on:** April 13 2023, 21:41 »

I was just digging around for a photo to see where I would attach an accumulator... only to see that indeed, there already is (a small 1 litre on) one there!!

The thermostatic mixing valve at the calorifier I reckon is the answer here though (and I have wondered about the plumbing getting that hot also) and a thermostatic shower head also... although I guess that would mean replacing the whole shower tap assembly... blast - I just bought a new one and fitted the original shower tap from SVB.

What parts, specifically, did you buy? Thanks for the responses!

Yngmar · « **Reply #4 on:** April 13 2023, 22:14 »

Yup, that looks much like ours, except with nicer handwriting!

I bought mine off eBay Italia for €38 and it looks much like this one: https://www.ebay.it/itm/125877485737

That's for a rooftop vacuum tube solar water heating system, which were the only ones that had a high enough temperature range. Most of the household plumbing things weren't rated to 95°C either

Plus a couple adapters from the chandlery. You'll want to keep all metal fittings on the hot (calorifier) side, once it's mixed down it can go into the red Whale pipe. Add a T-piece somewhere convenient (calorifier feed) to get cold water for mixing in.

Ailatan · « **Reply #5 on:** April 13 2023, 22:17 »

Hi MagicalArmchair,
I am in the process of fixing my calorifier and I pretend to install a thermostatic mixing valve that I have just received

https://a.aliexpress.com/_EHVK4nD

MagicalArmchair · « **Reply #6 on:** April 13 2023, 22:19 »

Thank you! I dug out an old photo of the calorifier below:

I might try one of these from our friends at SVB: https://www.svb24.com/en/sigmar-marine-thermostat-mixing-valve.html

This should have most of the fittings... if it fits the tank. Did you need to drain the whole tank down first?

MagicalArmchair · « **Reply #7 on:** April 13 2023, 23:23 »

Quote from: Ailatan on April 13 2023, 22:17

Hi MagicalArmchair,
I am in the process of fixing my calorifier and I pretend to install a thermostatic mixing valve that I have just received

https://a.aliexpress.com/_EHVK4nD

These look good too - a fair bit cheaper than SVB and there are lots of positive reviews!!

Yngmar · « **Reply #8 on:** April 14 2023, 00:22 »

Quote from: Ailatan on April 13 2023, 22:17

Hi MagicalArmchair,
I am in the process of fixing my calorifier and I pretend to install a thermostatic mixing valve that I have just received

https://a.aliexpress.com/_EHVK4nD

Rated for up to 85°C, so not suitable for the MD22 engine.

Ailatan · « **Reply #9 on:** April 14 2023, 07:26 »

Yngmar, the valve can give you mixed water at a higher temperature of 85º but can admit water at 95⁰C. In any case I think that MagicalArmchair was thinking of showering the children, not cooking them. So 38⁰C will be perfect.
MagicalArmchair, my first approach to the problem was installing a regular mixing valve, like the one you have seen in SVB, but cheaper
https://a.aliexpress.com/_EvGQ5mj
At the beginning I was very happy because if the temperature of the calorifier is around 80⁰C then you multiply the amount of warm water.
The problem is when the water of the calorifier is not at that temperature but lower, imagine that you are sailing or anchored and you turned the engine off a few hours ago, then the regular mixing valve will keep the same ratio of hot/cold water so the mixing water will be lower than the desired temperature and you will need to access the valve (usually is not easy) and change the ratio.
So last week, when I already had the regular mixed valve installed, I realised this problem so I ordered the thermostatic valve, which I have just received. I pretend to install it this weekend.

Keweetoo · « **Reply #10 on:** April 14 2023, 09:26 »

Surejust.co.uk can supply the thermostatic valves to fit calorifier and their website has diagrams of the installation - https://www.surejust.co.uk/thermostatic-mixer-valves

MagicalArmchair · « **Reply #11 on:** April 14 2023, 22:13 »

Thank you all. Due to the sheer lunacy that is Brexit, SVB won't ship to the UK anymore unless the order is over 160 euros, so I have ordered the below from ASAPs.

https://www.asap-supplies.com/products/quick-calorifier-thermostatic-mixing-valve-kit-1-2-bsp-9-93055

The AliExpress one gets some great reviews, but I just worry about manufacturing controls and the last thing I want is this valve failing. We had a failure of a hot water pipe on my fathers boat when we were heading into the Inverness Firth - there were clouds of steam (that I mistook as smoke to start with!) billowing from the saloon, which focussed the mind!

I should only need a few extra Whale fittings to splice this in I think.

When cutting the feed into the tank, I'm guessing all the water from the calorifier is going to empty its 10 litres straight into the bilge. Hmm, I wonder if there is a way around this? Is there any easy way to empty the calorifier before I make this change? Or just lots of jugs and rags!!

Yngmar · « **Reply #12 on:** April 14 2023, 23:58 »

You can pump it out. I've found a small 12V water pump with a bit of in/out hose quite handy around the boat. Input hose down the top fitting, output hose in the sink. You can use your spare freshwater pump for this, but make sure you protect it with a strainer.

Ailatan · « **Reply #13 on:** April 16 2023, 18:25 »

I use this pump:
https://a.aliexpress.com/_EHSr0z5

MagicalArmchair · « **Reply #14 on:** April 21 2023, 09:55 »

Thank you all, I managed to, after much faffing, install this little kit, and it was rather good and contained all I needed. So this is what you get in the box:

The top bit screws onto the hot water side of the tank, the bottom onto the cold water pressurized side of the tank.

Drain the hot water tank, and yes, alas the main tank (the reason for this will become apparent).
Take off all Whale fittings from the hot water tank. You need to remove the non pressurised side as you can't tighten up the new T piece with it in place! (Hence we needed to empty out the water tank next door - I also realised how much sediment was in the bottom of it, so cleaned that out too!!)
Apply liberal amounts of PTFE:
Screw the T piece onto the bottom, pressurised side of the tank, and then put the non pressurised side back on.
Screw the thermostatic valve to the hot water outlet...
Connect the T piece and the valve together using the stainless flexible hose, being careful to not kink it.

Turn the water back on... and pray for no leaks!! Top tip here, check all the Whale fittings - I should have been less tight and replaced them - they are 20 years old after all. One was missing its o ring entirely!!

First bit of plumbing I've done that didn't leak first time... now to get the water really hot next time and see if it actually works...

Ailatan · « **Reply #15 on:** April 24 2023, 21:57 »

I've also almost finished the same job with my low cost kit.
The only problem is that one of the Whale fittings is leaking one drop per hour so I will change it next weekend.

MagicalArmchair · « **Reply #16 on:** April 25 2023, 23:09 »

Nice work! I kicked myself for not replacing all the whale fittings whilst I had them off. I did replace all the main rubber o rings in them though and so far everything appears watertight. I haven’t run the engine for any period of time to get the water really hot though, so we shall see…

Ailatan · « **Reply #17 on:** April 27 2023, 14:10 »

Hi MagicalArmchair,
I don't know why I thought that the O ring inside the Whale fittings were "special" but if replacing them is easy I can save some money that I will spend fixing something different

marioxp · « **Reply #18 on:** May 05 2023, 14:51 »

When I bought the boat, there was no thermostatic mixing valve, I installed it in the same way as you write in the previous posts.

Two cold water pipe enters the calorifier and a hot water pipe exits. There are two more pipes that go from the engine.

I put a T connection on the cold water pipe, I screwed the mixing valve on the hot water outlet. With a flexible hose, I connected the T connection and the mixing valve.

Yes, it also happened to me that the entire tank leaked into my bilge when I disconnected the pipes.

After I connected everything and checked all the connections for leaks, I started the syste.

Pump started turning on frequently without anyone consuming water,
it turned on every minute or even more often. Eventually water began to leak through the plug on the deck.

I have no idea why, Where did the water that flooded the stern tank come from? from the bow tank?

Why did the pump turn on often? Probably because felt a drop in pressure on the consumption side. But why?

Where I made a mistake? Does it matter which cold water pipe I connected the T fitting to?

Ailatan · « **Reply #19 on:** May 13 2023, 22:33 »

Check this drawing.
May be you connect the hose that should go to the bilge to the pressure relief valve and the hose that should connect the pressure relief valve with the tank is in the same T connection that the water pump so the water pump is pressuring your water tank and that is the reason why it's working every now and then

Odysseus · « **Reply #20 on:** May 14 2023, 10:01 »

Change your approach, put in a other thermal controller, mine works great, I fitted the seperated shower with controller 10 year ago, also a shower curtain.

Odysseus
Bav 38