Tank Blankets

A little more on the tank heater saga.  I now have a clamp meter which showed the same currents that I had measured on 3 separate occasions in the middle of the night at the No 6 fuse, which is the fuse used by both tank heaters and the onboard water pump.  A-S and Sargent have both commented that my currents seem on the low side but neither has said what they should be.

Prior to making my last clamp meter measurements at the heaters, I opened, cleaned and dried the heaters 2 spade connectors.  The wastewater heater connections were OK but the freshwater ones were dirty and wet as were the adjacent spade connectors for the freshwater tank sensors which started showing 75% full even though the tank was empty at the time.  I found the insulation tape and black plastic cable tidies A-S had used were trapping water in them.  All are OK now.  

I have now found a much easier way of measuring the heater currents.  Put water in the tanks min 25%.  Open the EC700 and pull out a small black 2-pin plug from the PCB that is under the white X4 socket which is under the E3 socket shown in my earlier photo.  This disconnects the EC700 external temp sensor which means the CP shows minus 25 degrees.  This triggers an e-mail and SMS Frost Alert which I have never received before and isn't shown on AS Monitor or in any of its documentation.  At this time of year the conditions will be set to measure the current either at the No 6 fuse or on one of the wires connected to the heater using a clamp meter.  This is because the thermostat should already be closed due to previous low temperatures so no need to hold an ice pack against the thermostat.  Regardless whether the heater is connected or powered or not, the thermostat will stay closed until its temp rises to 18 degrees which it won't do at this time of year until it is warmed by a hair drier or the water in the tank which on my installation will take a very long time!  

My next test is to connect the waste water tank heater directly to the LB and then measure its current.  The label says it should be up to 5A.  Who know what I will discover.

Caraman wrote:As far as I am aware the official way into A-S for customer support is the A-S Service Centre at Willersey.  E-mails are generally acknowledged by either Karen or her assistant Venessa but as far as I can gather they are relatively non-tech.  Their normal response to a technical query seems to be get one of their Techs to phone you.  This is what happened to me but the Tech appeared unsighted on the Harmony Handbook and didn’t know how the tank heaters are fused.  I passed my query back to Karen who referred it to the factory.  That was 2 weeks ago and I have had nothing back.  I have found that the go to person in A-S is Dave Williams who was their sales manager but may have a broader role.  I am dealing with him now.

Whatever I discover I will share on the Forum as it is bound to interest someone.

Dave Williams left A-S at the beginning of this week.  He was the A-S Sales & Marketing Director.  He has passed by tank heater concerns to David Clarke who is the A-S Customer Service Manager - [You must be registered and logged in to see this link.].  I don't know if this is a new appointment.

I tested the wastewater tank heater on Sun.  When I powered it directly from the LB with the PX300 on and from a separate 13.6V PSU the current was still 0.8A.  I then found the wastewater tank heater wouldn't power from the EC700.  On Mon I filled the freshwater tank to see if its heater still worked from the EC700 and it did - still 1.3A.  I then discovered the wastewater tank heater also worked (0.8A) until I drained the freshwater tank and it stopped working.  So it appears the wastewater tank heater will only power from the EC700 if there is water in the freshwater tank.  I have asked Sargent if this is normal and am waiting a reply.

I have discovered that TankBlanket is the UK trademark for UltraHeat who manufacture the heaters in the USA.  I have asked UltraHeat what might be causing my 5A/5.5A heaters to only draw 0.8A/1.3A.  I am concerned that the heater installation instructions state that the heater's circuit must not be combined with any device with an electric motor which is what Auto-Sleepers has done with the onboard water pump.

I am hoping Auto-Sleepers will be able to explain why they have connected the 2 heaters and the onboard pump rated at 5.0A, 5.5A and 3.8/4.5A respectively to a 10A fuse (No 6).  TankBlanket/UltraHeat recommend a 15A fuse for each heater and Whale/Shurflo a 5A fuse for just the pump.  My fuse doesn't blow but nor will it if the heaters are only drawing 2.1A combined.

More to follow I am sure.

Sargent has sent me a new E3 socket/plug adapter with different pinning (blue/purple to pin 2, blue/brown to pin 5 and blue/green still to pin 1) and TankBlanket/UltraHeat are sending me two new tank heaters that should draw closer to the specified 5.0A & 5.5A.  They said the only reason for not connecting the heaters to the same circuit as an electric motor is to reduce the risk of the fuse blowing.  I hope to fit the new heaters in a couple of weeks time and test them with the pump running (to see if it blows the No 6 fuse) and with the new E3 adapter (to see if both heaters work independently of each other and whether there is water in the other tank or not).  For the test I will disconnect the EC700's external temperature sensor and if necessary use a bag of crushed ice to close each heater's thermostat switch.

Well the second E3 adapter from Sargent has resulted in each heater working independently of the other, regardless of the water level in the other tank, but now the wastewater heater button on the EC700 CP operates the freshwater tank heater and the freshwater heater button operates the wastewater tank heater.

The new heaters arrived from TankBlanket at the weekend.  I haven't fitted them yet but have tested them.  Here are my results:

Smaller TB90 - TH900UK – Nuevo’s 71 litres wastewater tank

	Amps A	Volts V	Watts W	Ohms
Original	0.81	13.35	10.81	21.5
Replacement	2.35	13.35	31.37	6.2
Label	5.0 stated	13.5 stated	67 stated	unstated

 
Larger TB121 - TH718UK – Nuevo’s 102 litres freshwater tank
 

	Amps A	Volts V	Watts W	Ohms
Original	1.22	13.35	16.29	13.5
Replacement	3.35	13.35	44.72	3.8
Label	5.5 stated	13.5 stated	75 stated	unstated

 
As can be seen the currents and therefore power outputs are much higher but both fall short of the values shown on the heaters' labels and on the TankBlanket website.  This explains why the 10A No 6 fuse doesn't blow when the Shurflo is running.

I am waiting to hear back from Sargent and the US manufacturer of the heaters.

Caraman wrote:
Dave Williams left A-S at the beginning of this week.  He was the A-S Sales & Marketing Director.  He has passed by tank heater concerns to David Clarke who is the A-S Customer Service Manager - [You must be registered and logged in to see this link.].  I don't know if this is a new appointment.

I have just received the e-mail below:

This email address (David.Clarke@auto-sleepers.co.uk) is no longer in use.

For urgent Warranty issues, please contact Robin Watson or Madalina Filote
For Service or Technical, please contact Karen Stevens ([You must be registered and logged in to see this link.])
For Parts issues, please send an email to [You must be registered and logged in to see this link.]

My conclusion.  It has become clear that just because a tank heater button is lit on the EC700 CP, it doesn’t mean the heater is working properly.  The only way to be sure of this is by testing, with each tank >25% and <25% full and with a DC clamp meter at each heater or second best by substituting the No 6 fuse with an ammeter and feeling for heat on the pad which isn't easy.  My clamp meter tests revealed 4 faults which I have made A-S aware of:
 
1.   The A-S and Harmony handbooks give different accounts how the tank heaters work.  The A-S handbook refers to an isolation switch and LED that doesn’t exist and does not explain that the EC700 will only send power to a heater if the van is connected to an EHU or whilst the engine is running and for up to 15 minutes after it has stopped, if the external air temp is <2ºC and if the tank sensor shows at least 25% full.  The Harmony handbook does explain this but not that each heater has a thermostat switch that will be open if its temp is or was 18ºC and hasn’t dropped to 6.7ºC since.  The Harmony handbook also wrongly states that the No 6 fuse covers the pumps when it covers the tank heaters and only the onboard pump.  The external pump is covered by the No 5 fuse.
 
2.   Sargent’s EC700 E3 harness plug under the PSU was incorrectly wired.  It was green/blue pin 1, green/brown pin 2, green/purple pin 3.  This made both heaters work as if they were one but only if the freshwater tank heater button was lit and only if both tanks were at least 25% full.  This meant if the wastewater tank was empty, which it could easily be, the freshwater tank heater didn’t work even though its button was lit and the tank >25% full.  Sargent corrected this FOC with a second adapter that moved the green/purple from pin 3 to pin 2 and the green/brown from pin 2 to pin 5.  This revealed fault 3 which wasn't apparent before.
 
3.   Sargent’s EC700 harness beneath the van has cross-wired the heaters so the wastewater tank heater is switched on by the freshwater heater button and the freshwater tank heater is switched on by the wastewater heater button.  Apparently there is no remedy other than to re-wire the heaters which is what I intend to do. 
 
4.   As reported earlier, the heaters installed by A-S were drawing very little current.  UltraHeat arranged for replacements to be sent to me FOC.  I only tested these for a few seconds as they were not installed.  I found the currents to be much higher but still less than shown on their labels.  UltraHeat has said that the heaters need to be on for 30-45 minutes to heat-up and break them in before the full current is drawn, which will be less than shown on the labels.  This is as well as if they drew 10.5A combined it would almost certainly blow the 10A No 6 fuse when the pump is running which would be fault No 5.  
 
When I install the new heaters, I’m going to insulate over them and the bottom of the tank with a cut down camping mat trapped in place by the tank straps.  This will improve the heaters’ efficiency and effectiveness and help protect them.  However, it will make them difficult to test in warm weather as the thermostat won’t be accessible.  This means I may have to wait for the return of cold weather before I can retest them over a longer period.  Whatever, they should be a big improvement.
 
Thanks go to mrfixit4u as without his post on 21 Jan I wouldn’t have found all this out and therefore been able to share it on the Forum.  I also wouldn’t have cleaned and sealed the underside spade connectors for the tank sensors and heaters and the onboard pump, which in some cases were mucky and damp.

A small update.  I decided not to rewire the heaters and instead have reverted to the first adaptor that Sargent sent me.  All this means is that the wastewater tank heater won't work if there isn't at least 25% water in the freshwater tank.  This doesn't bother me as I will not use the wastewater tank heater as it will not stop the drain pipe and tap from freezing.  Instead I will leave the tap open draining into a bucket if there is any chance of it freezing.  So I have now fitted both replacement tank heaters on the freshwater tank.  This along with the added insulation to the base of the tank should cover the coldest of conditions.  I'm also improving the insulation on the two pipes running from inside the van to the side of the tank.  Out of interest this photo shows the original freshwater tank heater opened up.  The metallic heating strip and thermostat are clear to see.  It's now in the bin!


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Now the temperatures have dropped it’s a good time to test the EC700 external water tank heaters as the heaters’ thermostat switch should by now be in the closed/on position and will stay that way unless their temperature rises to 18 degrees.  It’s still best to disconnect the EC700’s external temperature sensor unless the tests are in freezing conditions which will probably be at night.  The current flowing at each tank heater should be recorded with a DC clamp meter for each of the following conditions so 12 readings in total:
 
1.         Fresh >25%, Waste <25%
a.         Fresh ON, Waste OFF
b.         Fresh OFF, Waste ON
 
2.         Fresh >25%, Waste >25%
a.         Fresh ON, Waste OFF
b.         Fresh OFF, Waste ON
 
3.         Fresh <25%, Waste >25%
a.         Fresh ON, Waste OFF
b.         Fresh OFF, Waste ON

The hardest part is climbing under the van to take the readings!

Bilbobaggins wrote:Being a non technical and basically lazy sod, the first winter we had the van I stood at the main control panel one cold day when I had water in both tanks, set panel to show current draw on leisure battery, then switched tank blankets on, current draw increased. Switched waste blanket off using switch above ec500 under offside bench, current draw dropped but not to original level. Switched off at main control panel and draw returned to original level.

I think I therefore satisfied myself both tank blankets worked. I then drained the water system down for winter with my curiosity itch scratched. Haven't switched them on again since

I can't comment on the EC500 as I don't have one.  The faults I discovered were on the EC700 and its harness, so this thread is primarily for those that have the EC700.  I like you assumed my tank heaters were working properly but earlier this year discovered that when the waste water tank was less than 25% full, it stopped the fresh water tank heater from working even though it was turned on at the EC700 CP.  This is a concern as its quite normal for the waste water tank to be empty when the fresh water tank is full.  Indeed, in freezing conditions it is sensible to keep the waste water tank empty as its heater will not stop its drain pipe/tap from freezing.

I think the differences are the EC700 set up doesn't have a separate switch for the waste water tank heater.  Both heaters are switched on and off on the EC700 CP.  Although the heater buttons may be lit, the EC700 doesn't send power to either heater if its temperature sensor detects the air temperature is 2 degrees or more, or, if the tank sensor is not showing at least 25% full, or, if not connected to an EHU with the mains charger on , or, if the engine is not running.

gassygassy wrote:I need to check my tank heaters obviously. I think they should be powered via a fuse, and you could measure the current drain by removing the fuse and sticking an ammeter across the connectors. Or is that too simple? I am of the EC700 variety of Sargent.
I am more concerned with the boiler than the tanks. If the boiler freezes the water will expand and blow the water jacket, but I would have thought that if the contents of a water tank were to freeze, the expansion of frozen water would be taken up easily within the tank.
Or are your concerns that you cannot make a cup of coffee from a frozen water tank? I see some of the benefits in having an inboard water tank as other manufacturers fit.
I'll get back to my job of adding a 25 litre extra tank tomorrow so I'll check the boiler and hope it hasn't burst.  If it has, I wonder what steps to take to prevent it. I have drained it using the blue diamond 3 way dump valve so I'm hopeful it is OK. . . . . but . . . . .I have added a Shurflo pump fed from the submersible pump. The Shurflo will undoubtedly include a non return valve so anything on the high pressure side of it will still contain water - or ice.

As explained earlier in the thread, the tank heaters are fused through the No 6 10A red fuse which it shares with the on-board water pump.  I did measure the current across the fuse holder but was concerned it could damage my relatively cheap multimeter and it didn't indicate which tank heater was working.  For example, when I fitted the second adapter that Sargent sent me, the hot water tank heater button on the EC700 CP operated the waste water tank heater and the waste water tank heater button operated the fresh water tank heater!  

The tank heaters should be fitted under the tank as close as possible to the submersible Whale pump if it has been left in place or the open end of the pipe if it's been removed.  This is to ensure that water does not freeze at that point.  If it does freeze at that point there will be no water supply.  Making a brew is easy as you can fill the kettle from a tap on site or a water bottle but having a shower, washing up and flushing the toilet is harder.

For those who don't drain down after every trip, including during the winter, the Truma frost safety valve should open when it drops to about 3ºC and it can't be closed again until it has risen to about 7ºC.  An aeration valve fitted to the hot water outlet at the top of the Combi should allow air into the tank to allow the water to drain out.  However, this will not allow water trapped in the hot and cold water pipes leading to the taps to drain.  If the Shurflo pump is close to the Truma valve and slightly above it, I believe most of the water on its outflow side, which will no longer be pressurised, will find its way out through the open valve.  However, this will still leave water in the diaphragm pump itself, its filter and the inflow pipe from the fresh water tank.  This is why it's far preferable to drain down manually before there is a risk of freezing, open all the taps, remove the filter and pump air through the diaphragm pump for a minute or so.  Water will only flow through a diaphragm pump when its motor is turning and only in one direction.  They don't have or need non return valves.

The Shurflo manual says that for winter storage you should disconnect both the inflow and outflow pipes on the pump and then pump air through it.  I only remove the filter bowl but I did rearrange the outflow piping so there was a slight incline to the Truma drain valve.  My Shurflo packed up after 4 months.  We had gone to a site when the temp had been well below zero.  When I tried to fill the HW tank the pump wouldn't work.  I think it could have been frozen residual water in the pump had caused it to seize.  Willersey didn't think so and replaced it under warranty.  I had a similar experience earlier this year.  The pump made a click but nothing else.  I used a fan heater to gently warm up the pump and the nearby Truma valve and after a while all was well.  As a result of these two experiences and when the original Whale submersible packed up after 4 days along with the Truma, we always carry a small water container and other than in the summer a fan heater.  The fan heater is also good at clearing the frost and internal condensation from the cab windows at the start of a cold weather trip and we used it a short time ago when one of the Truma heating elements packed up.