Draining Rads with a Webasto Top Evo system.

[-Cookie-]

Had the system 3yrs now and the radiator water level is just below the min line. So i want to drain and replace with new water/antifreeze rather than just top up with water. It heats my tap water, and runs my rads. I have 3 rads and the one furthest from the heater has a drainage tap near it (15mm plastic pipe).

 

My question is, is it purely a matter of draining it, closing tap and refilling via the header tank?

or do i need to close of any other parts of the system? repressurise? etc

 

 

[BEngo]

Drain off, refill with mixed antifreeze.  Bleed  radiators and calorifier loop while filling.

Run to operating temperature. Check everything is getting hot, especially calorifier

Recheck level.

N

[Jen-in-Wellies]

20 minutes ago, -Cookie- said:

Had the system 3yrs now and the radiator water level is just below the min line. So i want to drain and replace with new water/antifreeze rather than just top up with water. It heats my tap water, and runs my rads. I have 3 rads and the one furthest from the heater has a drainage tap near it (15mm plastic pipe).

Is the reason you want to drain it because it is below the minimum line? Apologies if that isn't what you meant, but that is how it reads to me and it doesn't make sense.

[-Cookie-]

4 minutes ago, Jen-in-Wellies said:

Is the reason you want to drain it because it is below the minimum line? Apologies if that isn't what you meant, but that is how it reads to me and it doesn't make sense.

Well its mainly to refill with antifreeze/water and just thought it was a good idea after 3 yrs of toppping up with just water

 

8 minutes ago, BEngo said:

Drain off, refill with mixed antifreeze.  Bleed  radiators and calorifier loop while filling.

Run to operating temperature. Check everything is getting hot, especially calorifier

Recheck level.

N

ok thanks. its the calorifier loop bit that im not sure about, lots of pipes and im not confident with it. just my look a flood boat and messs up my heating as the cold nights draw in  🙃

 

[Jen-in-Wellies]

6 minutes ago, -Cookie- said:

Well its mainly to refill with antifreeze/water and just thought it was a good idea after 3 yrs of toppping up with just water

 

ok thanks. its the calorifier loop bit that im not sure about, lots of pipes and im not confident with it. just my look a flood boat and messs up my heating as the cold nights draw in  🙃

 

Understand now. Yes it makes sense to get back to a known percentage of antifreeze. A good idea to top up with antifreeze/water mix of your preferred ratio in future. It is the corrosion inhibitors that wear out, not the antifreeze component.

[BEngo]

9 minutes ago, -Cookie- said:

its the calorifier loop bit that im not sure about, lots of pipes and im not confident with it. just my look a flood boat and messs up my heating as the cold nights draw in  🙃

 Before you start draining, sort out which pipe does what on the calorifier:

Run the heating so there is hot water.

 

Turn off the heating and leave for an hour or two so the pipes to the rads go cold.

 

Turn on a hot tap.  One pipe from the cal will get hot.  This is the water outlet. Turn off tap.

 

Turn on the webadsto.  One pipe will get hot at the calorifier.   This is the heating inlet pipe.

Wait.  Another pipe will get warm to hot.  This is the heating outlet.

 Label the pipes so you dont need to repeat the check.  Turn off webadsto.

Drain down when cool.

 

After refilling if the calorifier pipes get hot inlet /warm outlet,  all is well.  Pour beer.  Relax.

 

If not just undo the fitting on the heating inlet pipe, a little, so the air comes out then, when water appears,  re-tighten, followed by the same thing for the heating outlet pipe. Have a few old towels handy in the event of water escape.

 

N

[-Cookie-]

5 minutes ago, BEngo said:

 Before you start draining, sort out which pipe does what on the calorifier:

Run the heating so there is hot water.

 

Turn off the heating and leave for an hour or two so the pipes to the rads go cold.

 

Turn on a hot tap.  One pipe from the cal will get hot.  This is the water outlet. Turn off tap.

 

Turn on the webadsto.  One pipe will get hot at the calorifier.   This is the heating inlet pipe.

Wait.  Another pipe will get warm to hot.  This is the heating outlet.

 Label the pipes so you dont need to repeat the check.  Turn off webadsto.

Drain down when cool.

 

After refilling if the calorifier pipes get hot inlet /warm outlet,  all is well.  Pour beer.  Relax.

 

If not just undo the fitting on the heating inlet pipe, a little, so the air comes out then, when water appears,  re-tighten, followed by the same thing for the heating outlet pipe. Have a few old towels handy in the event of water escape.

 

N

Thank you sooo much! this is the exact kind of idiot proof guide I need. hopefully it'll be beer sooner rather than later 🍻

 

21 minutes ago, Jen-in-Wellies said:

Understand now. Yes it makes sense to get back to a known percentage of antifreeze. A good idea to top up with antifreeze/water mix of your preferred ratio in future. It is the corrosion inhibitors that wear out, not the antifreeze component.

Yeah, id just topped up a bit here and there after normal lose/rad bleeding/and a tiny leak i had. used only water as was advised it anti/water dont mix that well in system and really needs doing before filling.

[David Mack]

28 minutes ago, BEngo said:

Turn on a hot tap.  One pipe from the cal will get hot.  This is the water outlet. Turn off tap.

 

Turn on the webadsto.  One pipe will get hot at the calorifier.   This is the heating inlet pipe.

Wait.  Another pipe will get warm to hot.  This is the heating outlet.

In general, the highest pipe connection on the calorifier will be the domestic hot water out, and the lowest will be the cold water in. The two* connections between will be the heating coil from the webasto. Either connection could be the in and the out, depending on how it has been plumbed, but it doesn't really matter which is which.

You should also have a pressure relief valve connection near the top. This probably has a red knob on it and a short length of pipe or hose which may drain to the bilge or to a skin fitting. 

Your calorifier may also be fitted with a mixing valve on the hot water outlet, which blends hot water from the calorifier with cold water from a connection near the cold water inlet, to ensure the domestic hot water doesn't reach scalding temperatures.

 

* Your calorifier may have 4 intermediate height connections, two as described above and two connected to the engine cooling water circuit so that the calorifier can also be heated by the engine. If this is the case it should be fairly obvious which are which as two pipes will run towards the engine and two towards the webasto.

[LadyG]

Engine

I have been putting a small amount of Prestone into my engine coolant, because i want to keep coolant fresh. Prestone is universal, yellow.. It seems to always maintain same level.

Webasto

One radiator is warmer than the other, which suits me fine .

Could or indeed should  I  drain four litres from radiators, and replace with Prestone.

I have come to the conclusion with this boat " if it ain't broke...."

[BEngo]

What is in the radiators now? When was it last fresh?

 Adding a little fresh coolant is pointless, unless you are topping up a leak or after an air bleed.

If the existing liquid is an antifreeze mixture which is less than five years old, leave well alone apart from topping up for which Prestone should be OK..  Then drain it all and replace with a suitable antifreeze mix once it is five years old. Check the coolant you pick is good with the Webasto.

 

N

 

 

[LadyG]

I don't know when the Webasto was fitted. It needs draining and changing, once I am near assistance.

I would tend to stick with Prestone, so only one coolant, would Prestone not be suitable?

I don't use the webasto every day 

 

 

 

Edited September 20, 2023 by LadyG

[Oz Mandius]

Hi all, could someone let me know what the correct coolant mix should be for a Thermo Top Evo. When I took the boat over the previous owner said it was neat coolant, but I’m not sure. I’m having hot water problems with the Webasto and don’t know if this is a contributing factor. 

[cuthound]

6 minutes ago, Oz Mandius said:

Hi all, could someone let me know what the correct coolant mix should be for a Thermo Top Evo. When I took the boat over the previous owner said it was neat coolant, but I’m not sure. I’m having hot water problems with the Webasto and don’t know if this is a contributing factor. 

 

I filled my Webasto with a 50% mix of water and antifreeze but found the radiators wouldn't get hot until I drained it all out and refilled with a 25% antifreeze 75% water solution.

[Tracy D'arth]

7 minutes ago, Oz Mandius said:

Hi all, could someone let me know what the correct coolant mix should be for a Thermo Top Evo. When I took the boat over the previous owner said it was neat coolant, but I’m not sure. I’m having hot water problems with the Webasto and don’t know if this is a contributing factor. 

Elucidate on " hot water problems" please.  No hot water? Too hot?  cold radiators?   Normally a maximum of 25% antifreeze. 20% will be enough.

[system 4-50]

1 hour ago, Oz Mandius said:

Hi all, could someone let me know what the correct coolant mix should be for a Thermo Top Evo. When I took the boat over the previous owner said it was neat coolant, but I’m not sure. I’m having hot water problems with the Webasto and don’t know if this is a contributing factor. 

Neat antifreeze would definitely cause problems!!!

[JoeC]

I drained my system and filled with water and used it for a while to give it a flush. Then drained and did the same again before doing the final drain and filling with antifreeze. Just helped to get rid of all of the old antifreeze and clean out any bits in the system.

[Tony Brooks]

1 hour ago, JoeC said:

I drained my system and filled with water and used it for a while to give it a flush. Then drained and did the same again before doing the final drain and filling with antifreeze. Just helped to get rid of all of the old antifreeze and clean out any bits in the system.

 

It might be clearer to newbies if you had said "filling with 25% antifreeze mixture", or 30% if you wish. Certainly not neat antifreeze, which is what this thread seems to involve.  FWIW you could have added a couple of pots of car cooling system cleaner additive to the water you ran with for a (short) while.

[Tracy D'arth]

Was perhaps filling with already diluted AF, premix, but its an expensive way to buy water.............................................

[Oz Mandius]

On 13/04/2024 at 19:53, Tracy D'arth said:

Elucidate on " hot water problems" please.  No hot water? Too hot?  cold radiators?   Normally a maximum of 25% antifreeze. 20% will be enough.

Webasto doesn’t produce hot water despite feeding into the calorifier. The radiators belt the heat out though. I’ve tried turning the rads off to test to see if that improves the hot water problem but to no avail. 

[Tony Brooks]

Have you followed the pipes to the calorifier in case there is a valve? If not, I would suspect an airlock in the calorifier Webasto coil or its pipe work.

[Oz Mandius]

17 minutes ago, Tony Brooks said:

Have you followed the pipes to the calorifier in case there is a valve? If not, I would suspect an airlock in the calorifier Webasto coil or its pipe work.

Thanks Tony. No valve seen yet on the pipe work which is easily accessible, much of it runs behind the skirting board but though I suspect there’s no valves behind there I’m still going to check. 

[Tony Brooks]

27 minutes ago, Oz Mandius said:

Thanks Tony. No valve seen yet on the pipe work which is easily accessible, much of it runs behind the skirting board but though I suspect there’s no valves behind there I’m still going to check. 

 

Look for upward or downward bows in the pipes that might allow them to trap air. If a pipe slopes upwards or has a vertical leg where it connects to the calorifier I would not be surprised if air was trapped there. Manipulate any bows to allow air to move to the highest point it and then loosen a connection to see if air comes out.

[Alan de Enfield]

14 hours ago, Oz Mandius said:

Webasto doesn’t produce hot water despite feeding into the calorifier. The radiators belt the heat out though.

 

Am I understanding correctly ?

1) The Webby provides hot water to the radiators , they get hot ?

2) There is no hot water coming out of the sink / shower taps ?

 

So the webby is working and producing hot water, it is just not getting to the taps ?

[Hudds Lad]

I'd deffo look for a valve, we had the opposite problem with our MV Hydro 5-S where we got hot water but rads were stone cold.

Turned out to be a closed valve that we didn't notice as the big red wheel had been removed  

[Oz Mandius]

On 16/04/2024 at 20:27, Oz Mandius said:

Webasto doesn’t produce hot water despite feeding into the calorifier. The radiators belt the heat out though. I’ve tried turning the rads off to test to see if that improves the hot water problem but to no avail. 

Hi all, it looks like this is now sorted. I bled the system, which didn’t take much to be honest and re-run the unit with all the radiators turned off. After 40 minutes the water coming out of the hot tap was like lava, so it appears that I now need to turn the rads off to get the water to the required temp which is no great shakes.  From now on if I’m just after hot water I’ll close off the rads and bang the Webasto on for 30 or so minutes. Thank you for all the suggestions and advice.