[dazmond]

this is for you a900!i bet it ends up longer than the hydroheat thread over the next month or so!

[Simon Trapani]

Yeh it’s got me interested today cos it’s bloody freezin!

[a900]

Haha. Better start trying to work out how to get these photos uploaded. Somehow I can upload PDFs.

For anyone interested. First one shows the size of the heat exchanger I used. I used one this size because I didn’t want one that was 2 small and not knowing what would be 2 small. So basically looked for one that was the same size as a Webasto plate heat exchanger or larger. When I add a second it will be much smaller to fill a gap on my board. As I really think it’s larger than needed but for the main hose I wanted to make sure I got the hottest temperature I could.

I’m working on a recirculation that switches the pump to a low speed the same as 11 on my controller and diverts the water back to the tank. So when I finish a job and drive to the next one or get distracted chatting with customers I can keep the heater idling so it doesn’t shut down. (Learnt they use less fuel this way) This will be on a switch for now but might use a wireless fob and control the electric reel with it too. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F131730091890

This will save me time turning my pump down and plugging the reel hose in to recirculate every time the van is moved.

Frostat to come. Which will use most of the circuit set up for the recirculation but use a little board that you can get for £2 that can turn the pump and heater on and off at whatever temp I set. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F283139826056

[dazmond]

that heat exchanger is MASSIVE compared to mine from grippatank!

[Smudger]

sorry, thick here - how does it work ? or are there other parts needed ?

Darran

[Spruce]

Haha. Better start trying to work out how to get these photos uploaded. Somehow I can upload PDFs.

For anyone interested. First one shows the size of the heat exchanger I used. I used one this size because I didn’t want one that was 2 small and not knowing what would be 2 small. So basically looked for one that was the same size as a Webasto plate heat exchanger or larger. When I add a second it will be much smaller to fill a gap on my board. As I really think it’s larger than needed but for the main hose I wanted to make sure I got the hottest temperature I could.

I’m working on a recirculation that switches the pump to a low speed the same as 11 on my controller and diverts the water back to the tank. So when I finish a job and drive to the next one or get distracted chatting with customers I can keep the heater idling so it doesn’t shut down. (Learnt they use less fuel this way) This will be on a switch for now but might use a wireless fob and control the electric reel with it too. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F131730091890

This will save me time turning my pump down and plugging the reel hose in to recirculate every time the van is moved.

Frostat to come. Which will use most of the circuit set up for the recirculation but use a little board that you can get for £2 that can turn the pump and heater on and off at whatever temp I set. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F283139826056

It would also help you to have a bigger header tank as it becomes a heat reservoir and extra heat buffer.  It takes more water to heat up and gives you more flexibility in that half heat mode window.

[a900]

Spruce that’s something I’ve been thinking about. It’s quite a small reservoir really. It does have its advantages. Should result in faster warm ups. But in reality to heat the extra 5l or something isn’t going to be long.

Although I have thought about this and I’m not sure how much different it would make. I’m still taking out the same energy from the reservoir whatever the size through the heat exchanger. So a larger reservoir would just result in less temp dip but same energy back in to get to the shut down level.  Surely? Feel this one is confusing me 😂 sometimes like that then all of a sudden get it

How long does your take to shut off? Does it have any system to keep it running on idle?

[a900]

sorry, thick here - how does it work ? or are there other parts needed ?

Darran

Put simply 2 water circuits

Heater circuit or loop. Water in the heater through to the exchanger fed back to a reservoir continues.

Pole  Circuit. Water runs through the heat exchanger taking heat from the heater curcuit and heads down your hose and to your pole

[windowswashed]

Basically the same principal as an indirect calorifier 

[Spruce]

Spruce that’s something I’ve been thinking about. It’s quite a small reservoir really. It does have its advantages. Should result in faster warm ups. But in reality to heat the extra 5l or something isn’t going to be long.

Although I have thought about this and I’m not sure how much different it would make. I’m still taking out the same energy from the reservoir whatever the size through the heat exchanger. So a larger reservoir would just result in less temp dip but same energy back in to get to the shut down level.  Surely? Feel this one is confusing me 😂 sometimes like that then all of a sudden get it

How long does your take to shut off? Does it have any system to keep it running on idle?

I don't have a diesel heater in the van atm. I'm going to fit mine when I get my 'new' van sorted. (I wish I had a bit of warm water on occassions this winter so far - I'm not liking the stiff hoses or the cold hands.)

I'm just making that observation on the size of the tank because HeatWave and Purefreedom use a 12 liter tank. They they also do recommend not to fill it fully.

Here is what the Thermo90 manual says;

When the water temperature reaches 72ºC, the heater will switch to a lower output.  The combustion air motor speed and fuel pump delivery are reduced.

If the coolant temperature continues to rise by a further 10ºC, the heater will then automatically stop combustion, fuel delivery will cease and the flame within the combustion chamber will be extinguished.  The heater will then commence a 180 purge cycle.

The heater is now in stand-by mode.  The green operation light will still be illuminated and the water pump will continue to circulate the hot water.  The heater will automatically restart if the water temperature falls by 15 C, going through the same start cycle as before.
 
If you have a bigger header tank it will take the same heat delivery from the  Webasto longer to raise the water that extra 10 degrees before the heater goes into shutdown mode.

I have an additional 10 plate heat exchanger which I want to add into the heating circuit. This will be have its own pump controlled by a digital temperature controller.  Hot water pumped through this heat exchanger will return to the van's tank. The idea is that the controller will be set to switch on this additional pump at say 80 degrees and switch off just before the heater would normally go back into full heat mode. (I don't know exactly at what temperature the heater is programmed to return to full heat mode, but on the Thermo Top C its 68 degrees.) I will also put a cheap PWM controller into the circuit to reduce the pump's flow rate.  What I want to do is keep the pump kicking on and off to keep the burner in this half heat window.

My problem is that I don't find window cleaning very mentally stimulating, but I do love talking to our customers. This is why I need the automatic heat reduction included.

Yes, having a bigger header tank with more water will take longer to heat, but PureFreedom have suggested its best to start your heater before you get to your first customer. Most of our customers are a 10 to 15 minute drive away so starting the heater at home before setting off is what we would do. The van's alternator will also supply the initial current surge need to start the boiler.

Dazmond manually redirects heated water to his tank to keep his T90 running continiously. I want to do the same electronically.

[a900]

Ok so I’ve got it now. You will have more energy in your heating system with a bigger tank but it will take longer to run the pole before the coolant temp drops enough to kick the pump on compared to me. (So it will sit at idle longer) So loosing a larger amount of energy out the coolant loop which when the flow is stopped gives longer for the heater to get it to temp as a buffer.

But say an extra 5l water in the loop and say the idle is 20c lower than full power. Using the calculator it would take 0.11kw to heat that volume.

9.1 kw heater running at full power. So in 1 minute it could pridice heat energy at 9.1/60= 0.15kw per min.

So in my mind it would only extend the buffer time by a minute. How long do people get with their grippatank heaters before they shut off?

I’m quite sure tho that the heater runs at 7.6kw when the temps are higher already. So 0.12kw per min

Am I missing something?

As far as recirculation goes. I think your plan of the extra exchanger is the best. I’m planning to wire a DPDT relay that has the pump as the output. With the switched input coming from the controller and the second from a PWM board that runs the pump at minimum neeeed to keep the heater idling. At the same time it will also operate a normally closed solenoid valve on the output of the heat exchanger to recirculate water back to the main tank. I thought about how this could be temp controlled but I don’t know a way to switch the pump and solenoid back when I need flow out the pole automatically with this set up.

With another heat exchanger it could be wired to a temperature control circuit which would recongnise when the temp drops again through using the pole

I was trying to avoid an extra heat exchanger for packaging reasons 😂

[a900]

As far as a recirculation pump for an additional heater ..

This would work https://m.banggood.com/DC-12V-5_5M-1000LH-Brushless-Motor-Submersible-Water-Pump-p-1118173.html?gmcCountry=GB&currency=GBP&cur_warehouse=CN&createTmp=1&utm_source=googleshopping&utm_medium=cpc_union&utm_content=2zou&utm_campaign=ssc-gb-en-all&gclid=EAIaIQobChMIiJnZo6-h3wIVZr7tCh3yUQZBEAQYAiABEgLWH_D_BwE

[Spruce]

As far as a recirculation pump for an additional heater ..

This would work https://m.banggood.com/DC-12V-5_5M-1000LH-Brushless-Motor-Submersible-Water-Pump-p-1118173.html?gmcCountry=GB&currency=GBP&cur_warehouse=CN&createTmp=1&utm_source=googleshopping&utm_medium=cpc_union&utm_content=2zou&utm_campaign=ssc-gb-en-all&gclid=EAIaIQobChMIiJnZo6-h3wIVZr7tCh3yUQZBEAQYAiABEgLWH_D_BwE

You could use any 12v water pump as long as it delivers enough 'head' to pump water back onto where your connector is, usually at the top of your tank. I thought of my Shurflo pump as it will handle 60 degrees and ticks all the other boxes as well.

It would also have to be able to be mounted securely. That pump linked to would need those suction cups replaced with something better.

[Spruce]

Ok so I’ve got it now. You will have more energy in your heating system with a bigger tank but it will take longer to run the pole before the coolant temp drops enough to kick the pump on compared to me. (So it will sit at idle longer) So loosing a larger amount of energy out the coolant loop which when the flow is stopped gives longer for the heater to get it to temp as a buffer.

But say an extra 5l water in the loop and say the idle is 20c lower than full power. Using the calculator it would take 0.11kw to heat that volume.

9.1 kw heater running at full power. So in 1 minute it could pridice heat energy at 9.1/60= 0.15kw per min.

So in my mind it would only extend the buffer time by a minute. How long do people get with their grippatank heaters before they shut off?

I’m quite sure tho that the heater runs at 7.6kw when the temps are higher already. So 0.12kw per min

Am I missing something?

As far as recirculation goes. I think your plan of the extra exchanger is the best. I’m planning to wire a DPDT relay that has the pump as the output. With the switched input coming from the controller and the second from a PWM board that runs the pump at minimum neeeed to keep the heater idling. At the same time it will also operate a normally closed solenoid valve on the output of the heat exchanger to recirculate water back to the main tank. I thought about how this could be temp controlled but I don’t know a way to switch the pump and solenoid back when I need flow out the pole automatically with this set up.

With another heat exchanger it could be wired to a temperature control circuit which would recongnise when the temp drops again through using the pole

I was trying to avoid an extra heat exchanger for packaging reasons 😂

Daz did say somewhere what flow setting he used on his Spring controller to keep the heater running.

Remember, the specs say that in reduced heat mode the heater is producing 1.8kw of heat. What they also don't tell you is that half the heat produced is wasted through the exhaust.

On my Thermo Top C 5.2kw heater, I managed to raise the temperature from 9 degrees to 35 degrees at a flow of 1.5lpm. According to the formula that required 2.65kw so the remaining heat was being lost elsewhere. That exhaust was very hot.

This wasn't a scientific experiment. Before I set up a test rig I could never understand why cleaners struggled with heat using  a 5.2kw  Thermo Top C as a heat source. According to the formula they should have been able to supply enough heat to provide warm water for 2 cleaners.
When I realised that what I thought would work on paper didn't work in practice, I shelved the idea.

[P @ F]

Hey Spruce , do you have a link to this formula please ?
I can build and tinker for England but maths was never my strong point !

[Spruce]

Hey Spruce , do you have a link to this formula please ?
I can build and tinker for England but maths was never my strong point !

 

I couldn't find an online calculator to do it for me. Someone did put up a link once but I have tried to google it to no avail.

Calculate the kilowatt-hours (kWh) required to heat the water using the following formula: Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of liters of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius.

So in my case;
4.2 x 90l (1.5lpm x 60 for an hour) x 26 (raising the temperature from 9 degrees C in the tank to 35 degrees C at the brush head) = 9828 ÷ 3600 = 2.73kwh. The Thermo Top C is 5.2kwh.

Its probably better than that as there would be a little heat lost to the environment with those copper pipes and from the sides of the heater itself.  I would have boxed the whole unit in to help retain that heat lost, but I could see that the heat loss was mininal when compared to the heat loss out of the exhaust of the boiler.

Another thing I failed to consider was that water flows quicker when its hot. So my controller set on 3 delivered 1.5lpm of water at the brush head when cold. The same controller on the same flow showed a marked increase of water flow at the jets when heated. But I failed to measure the amount lpm of water after it was heated. So for example, if the water flow increased from 1.5lpm to 2lpm, the outcome of my experiment is flawed.

.

[P @ F]

Right , with you sort of  ,
What is the 4.2 though       Told you I was fick

[P @ F]

Hold on , is 4.2 the coolant in the system ?

[Spruce]

Hold on , is 4.2 the coolant in the system ?

No. The 4.2 is part of the formula so that stays the same as does the 3600.

All you need to tell the formula is how much water you want to heat and how much the temperature rise required is.

So lets say you have my 1.5lpm of flow you want to heat and you need the temperature to rise to 45 degrees C from 9 degrees.

So we have 4.2 x 90 liters per hour x 36 = 13608  ÷ 3600 = 3.78kwh.

But also consider that this is a lot more complex than this. All this formula does is to take one single rise in temperature of 90 liters of water by 36 degrees. It doesn't take into account any form of heat loss.

If you let the system recycle that heated water then everything changes. Now you need the same amount of heat to raise the temperature of the water from 45 degrees C by 36 degrees so you now have 81 degrees C after your second pass.

I know this is confusing because I ran this system on full throttle and was only able to extract a temperature of 35 degrees. The water after the heat exchanger was cold so that says to me that as the water going to my brush was taking every scrap of heat from the boiler (transfer of heat from the internal hot water side to the side going to the brush.)

Now had I left the boiler to heat up the internal water circuit then it would have probably given me a much higher temperature at the brush head. Yes, I would have zapped more heat from the boiler circuit when I cleaned the back 2 upstairs windows, But when I switch my tap off to drag the hose to clean the side and front windows its giving the boiler a chance to recover the heat I've taken, putting it back into the header tank to store it for later when I start cleaning again.

Hence the reason why PF tell a purchaser to preheat the system so its up running and hot when the cleaner starts cleaning his first house.

Your gas heater works totally differently as it heats the water going to your brush in the internal heat exchanger. It only gets to do that once. It is a true heat on demand heater.

[P @ F]

I just looked at your setup you did and the thing that struck me was the amount of complex copper pipe you put in it that was not insulated , do you think this was a factor in losing so much heat and only getting 35 at the head .
Was that the only build or were there simpler ones first ?