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Sunamp not heating the water


Inchbyinch
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Hi All,

 

I temporarily commissioned my sunamp a few weeks ago, followed the instructions and was happy it was all working as it should. 

 

Now I have it wired up in a permanent arrangement, switching the solar through a time clock as I have no PV installed yet. I have an electrical meter on it to measure use. 

 

The problem is that now it doesn’t take any current and even when I run preheated hot water through it I’m getting cold water out. 

 

Hoping to move in next week with SWMBO and two toddlers next week and one more on the way??. So hot water must be going!! 

 

Thanks in advance, 

Ed

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Which Sunamp model is it? 

 

Is it a UniQ eHW?  If so, then check that the permanently on power is really on, and listen to hear if the power relay in the control box clunks on.  Also check that the heater power supply is on.  Also, look at the LEDS on the control board inside the box, as they will give a reasonably good diagnostic readout.

 

If you have a Sunamp PV, then there's a four core power cable and both the line wires need to be powered for the unit to work.  Clues as to problems with a Sunamp PV are to listen for the pump to see if it is running when power is on.  Also, there are four LEDs visible on the side of the box that are a pretty good indicator of status.  One problem that can make a Sunamp PV stop charging is an airlock in the pumped circuit.  It's very sensitive to air in the water, which upsets the ultrasonic flow sensor.  Another known Sunamp PV problem is the over-temperature switch operating.  This is on the heater tube and can be reset by isolating the power, opening the top cover, lifting off the neoprene foam insulation and checking to see if the over-temperature switch needs resetting by pushing the button in the centre of it.  If it's tripped then it will click and push in a bit.

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Which Sunamp is it?  Is it a Sunamp PV, as they are radically different to the Sunamp UniQ range?

 

If it's the Sunamp PV, then the first thing I'd check is that both the line wires in the four core cable have power, as both need to be powered for it to run. 

 

Next check to hear if the pump starts to run when power is turned on to both line wires - the pump will run for a short time then stop if there's an airlock or air in the water.

 

If nothing happens, and the lower two LEDs are on, then the chances are that the overheat switch has operated and will need to be reset as described above.

 

If you have a Sunamp UniQ then they are completely different and the LED diagnostics are only visible with the control box cover off, and there is no pump or other noises from the Sunamp unit, other than a sound a bit like a crisp packet being scrunched up when it first heats from cold, accompanied by the click of the power relay in the control unit switching on and off every 30 seconds or so during initial warm up.

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Sounds to me like there's no power getting to the heating element.  That's in a tube at the front of the unit at the top, and I have a feeling that the overheat switch may only be in the power feed to the heating element.  It's not air in the pipework, as when that happens the the lack of flow detected by the flow sensor switches the pump and heating element off.

 

I think it's worth isolating the power, removing the lid and the neoprene insulation and checking the overheat switch.  It's screwed to the side of the heating element tube, with two high temperature wires running to it.  Between the terminals there is a reset button.  Try pushing that in and see if it clicks to reset the switch.

 

After doing this, try the unit again to see if it fires up.  If it does, then there are a couple of possibilities as to the cause.  The first is that the overheat switch may have a fault.  There is a known issue with very early Sunamp PVs (earlier than mine) where a small number were fitted with a faulty switch, but I'm pretty sure all these were replaced.  The second possible cause is heat soak after the unit has been turned off.  This is an unusual occurrence, because it only happens if all the power goes off when the unit is hot and still heating the cells up.  Normally there is a pump over-run timer that keeps the pump running for a short time after the heating element has switched off, to remove the residual heat from the element.  If the power goes off to the whole unit (both power supplies) then the heating element tube can overheat from heat soak and cause the over-temperature switch to operate.  I had this happen a couple of times, and tracked it down to times when the power had been turned off when the unit was still heating.

 

If resetting this switch doesn't work, then more involved diagnostics are needed.  There is a diagnostics mode that you can access on the main circuit board, that will run through a sequence of checks and give an indication on the LEDs as to the possible problem, but it does involve working on the unit with power on and a cover off, so best to try the overheat switch reset first.

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Guest Alphonsox

I found SunAmp technical support to be very helpful when I had a similar problem with my PV unit. (eventually traced to an issue with the external timer unit feeding one of the two power wires). Well worth giving them a call.

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I've just dug out all the notes I made from conversations with Sunamp technical support. 

 

I can confirm that when the over-temperature switch operates the pump stays on and only the heating element stops working, so it sounds very much as if this switch needs resetting.

 

 

 

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My PV had similar issues and SunAMP  tech talked me through the test procedure. There is a small push switch on the pcb that starts the diagnostics and than result is shown via the leds.

 

Be careful as 240v is present

 

However i did find that the plugs on the pcb can come loose so check them.

 

Mine turned out to be a faulty heater that was replaced under the warranty

 

give them a ring as they were very good in sorting

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So a quick update here. I have opened up the unit and found what I think is the OT switch. A Small black switch facing the pump perpendicular to the heating element. InPressed that in but can’t say I heard a click or anything.

 

I then proceeded to re powered the unit and expected the unit to charge continuously but it heated for about 35 seconds (solar LED on solid) and the take a break for about a minute (solar LED blinking) and then started heating again. 

 

The element was getting very hot and the cooking again rapidly so I presume it was tripping out on an over temp.

 

I ran the hot water tap to draw some water through the heat battery and see would that release any potential issues. The hot water seemed warm, above body temp but certainly not at 65 Deg (the TRV was fully open)

 

I checked back at the unit and the providing heat LED was on and now the solar light was on solid, not switching on and off as it had done previously. 

 

I will await the final results in the morning but this exercise looks to have sorted it....whatever testing one would call that.

 

My main problem during the day is that I’m at work during the SA opening hours so can’t get chatting to them! 

 

Thanks for for all the help here....gave me the confidence to start playing with it.

 

r

ed

Edited by Inchbyinch
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5 hours ago, Inchbyinch said:

The element was getting very hot and the cooking again rapidly so I presume it was tripping out on an over temp.

 

I don't think it was tripping out on over temperature again or the switch you reset would have tripped.

 

It was doing what it's supposed to do as mentioned here on the forum previously. It "cycles" to gradually change the pcm state uniformly.

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4 hours ago, Onoff said:

 

I don't think it was tripping out on over temperature again or the switch you reset would have tripped.

 

It was doing what it's supposed to do as mentioned here on the forum previously. It "cycles" to gradually change the pcm state uniformly.

 

The Sunamp PV doesn't cycle the heater, it has a pump that circulates water through a primary charging circuit to the heat exchangers inside the cells and the heating element relay is on all the time that PV power is detected.  The pump controls allow for an over-run when the heater turns off, if there is still power to the unit from the always-on supply.  The snag is that if the always-on power to the unit fails, then the pump doesn't over-run to cool the heating element and it gets very hot from heat soak, which can then trip the over-temperature cut-out switch.

 

The other snag with the Sunamp PV units is that they have an ultrasonic flow sensor, that can be upset if there is any air in the system, which causes the unit to shut down.  Once the air is out of the unit and it's been running for a while, it's unlikely that air will cause any problems, but it can during commissioning I found.

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On 24/10/2018 at 06:05, Onoff said:

It was doing what it's supposed to do as mentioned here on the forum previously. It "cycles" to gradually change the pcm state uniformly.

The difference between the two units are simple. 

The early units didn’t get an immersion heater as such. The early development version ( the SAPV ) was just a closed cell with the only means of importing heat to the PCM being dealt with via the heat exchanger. Basically that means you need to heat water outside the cell and then send the heat backwards through the same heat exchanger that is then, in turn, used to export heat to DHW. The heat is produced by a very small Willis type inline water heater which has a pump and a flow switch. The pump speed regulates the flow so when the PCM is at or near frozen it runs slower to send the correct flow temp to the PCM. As the PCM heats through the pump return increases so the pump speed increases to pass water through the Willis heater quicker to maintain the correct flow temp. If the pump or flow is out of sync for whatever reason the Wilis can boil like a kettle and therefore the Willis OH ( overheat ) stat operates. As that’s seen as a terminal failure it requires manual resetting. 

 

In the newer, far far simplified UniQ range the immersion heater actually resides in the base of the cell, internally, and is surrounded by the PCM in the same way as the heat exchanger is eg 100% immersed / encapsulated. No need for pumps / Willis heaters / flow switches / PHE / and no need for all the inter-connective pipework necessary to convey ‘wet’ heat. 

 

As the SAPV is indirectly heating the PCM it can use variable flow & temp ( variable but continuous current ) to input a continuous flow of heat energy. 

The ‘complication’ that SA had to overcome with the SA UniQ unit is; as it has the immersion direct into the PCM it has the ability to immediately overheat the surrounding PCM which would destroy it. The ‘melt’ characteristic of the PCM doesn’t deal very well with intense / accuse heat energy being introduced from just one concentrated area ( that the contact surface of the encapsulated immersion achieves ). 

 

( For info, the PCM can be destroyed by putting too high a temperature into it. Basically you can cook and kill it with no possibility of recovery. This is why there is the need for modulated flow and heat control with the SAPV. A bit bit like you wouldn’t use a blow lamp to defrost the Xmas turkey as you’d burn and ruin the outside but the inside would still be frozen solid ). 

 

Therefore the UniQ Qontroller has a programmed pulsed output which is used to gently heat and melt the immediately surrounding PCM around the immersion. It pulses on every minute or so iirc and injects heat in chunks. When the lower thermistor registers heat the Qontroller ( I think ) then let’s rip with full bore heat input. So, every time you fully discharge an UniQ unit it will go back to what I call the ‘defrost cycle’ as described ( so is not a one time first switched on event, it’s an every heavy discharge > reheat event ;) ). 

 

The UniQ immersion also has an overheat stat, so terminal OH ( failure of the electronics to control the heat input for any reason ) would cause that to trip and isolate the immersion for safety.

 

The UniQ range with an ‘e’ prefix ( eg 'eDual' ) have an immersion and are primarily intended to be heated by electricity. Units without the prefix ( eg 'Dual' ) do not have an immersion and are to be heated indirectly ( by a boiler or ST / high temp ASHP etc ). 

 

Now, pay attention folks.....

 

An UniQ +I ( eg 'Dual+I' ) has an immersion. :S  This unit is meant to be heated indirectly ONLY but you can ( say if the boiler / other goes tits up ) go and then heat it TEMPORARILY with the immersion in the same way you can with an UVC for eg. You should not heat that unit indirectly and with the immersion simultaneously, so basically if you have solar PV available during the day and your boiler is running you shouldn't use the PV to fortify the boiler flow, eg it should be one or the other. That would require a changeover arrangement where excess pv injection then disconnected the boiler call for heat ( demand ) signal temporarily and accordingly. 

 

Oh, and there’s other configurations available too, but my thumb hurts now. 

 

If you think that’s a lot to remember then feel my pain. I’ve forgotten my kids names since working through the chuffing manual ?

 

Edited by Nickfromwales
bit of additional clarity on a couple of things
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1 hour ago, ProDave said:

Just a simple question having read the above.

 

If the immersion now goes through their own pulsed controller, HOW will that operate if you are trying to dump variable amounts of surplus solar PV to the thing?

 

 

It's not a problem, as the relay in the Sunamp control box works much like the thermostat in an immersion heater, so when the relay opens the PV diverter can't divert power, senses this, and so switches the power on continuously (as there is no load).  When the Sunamp main relay connects again, maybe 15 to 30 seconds later, the heating element starts drawing power and the PV diverter may then start switching power on and off again, depending on the excess being generated.

 

This warm-up cycle only happens when the Sunamp heat cell is completely exhausted and cold, so really only once during commissioning, and again if the power has been off for a long time.  Most of the time the PCM will stay liquid around the heating element and the cold start pulsing won't come on.  The duration of the cold start pulse period seems to be around 5 to ten minutes or so.  As soon as the lower temperature sensor in the heat cell reaches a warm enough level the cold start mode is disabled and the power relay stays on all the time.

 

One slight snag with the Sunamp Uniq models that have an electric heating element is that you can't tell whether or not the power relay is on.  I fixed this on mine by adding a 230 VAC neon indicator to the power relay A1 and A2 terminals, with the indicator fitted into one of the spare cable glands on the box.  I can now see at a glance whether the Sunamp is calling for heat or not, which is very useful, IMHO.

 

1034661655_Sunampindicatorlight.thumb.JPG.e2b038ce4ec0777d4105a9d50c51c13e.JPG

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1 hour ago, ProDave said:

Just a simple question having read the above.

 

If the immersion now goes through their own pulsed controller, HOW will that operate if you are trying to dump variable amounts of surplus solar PV to the thing?

As @Barney12 and I have just discovered, with the Apollo GEM in this instance, not very well at all :(.

As most PV diverters 'sniff' for the constant ( but variable ) flow of current, the SAPV was far more compliant with such external sensing. The UniQ setup is not that compatible IMO with the pulsed bursts of energy it initially requires to 'defrost' the PCM, so a little more thought is required.

I've yet to look properly at this, what with just about now getting to grips with the feasibility / functionality side of the SA itself first, so there are yet still some unanswered questions that I have to ask to the various diversion controller manufacturers. I tried to speak to the tech guy from Apollo but he had such a strong French accent and not the greatest of English I really struggled to convey questions ( with my welsh accent ) and get the answers. Got repeatedly told how amazing and diverse it was, but I left that conversation with probably more confusion than when I started it TBH.

The Mi Energy range of products will be my next port of call, so bear with me and I'll ( attempt ) to update here accordingly, but as you mention Dave, it ( the SA Controller ) would be far better and more universally integrated if it had a constant, albeit variable, flow of current at all times. I visited SA HQ on the 25th of this month and had a great opportunity to speak with Stuart Cunningham ( Training and Installations Manager ), Will Howell ( Production Manager ), and Trevor Cross ( UK Sales Director ) in their respective domains. Very interesting and informative, and demonstrates the huge mountain they've climbed to get this product to market. As a result of said visit, I have been told that other Qontrollers will make it to the market place as R&D allows, but obviously nothing will be released until its ready and proven fit for purpose.

@JSHarris, Immersion on / SoC and other indicators / more comprehensive displays etc are already in the mix ;) Please don't ask anything on that subject folks, as thats all I've been told.

 

The SA Controller has user definable settings, and one parameter is the depth of discharge where reheat will be initiated ( call for heat aka demand ). This can be set to 50% depleted, or 90% depleted so a range of differing ways to stave off the issues with the 'defrost' cycle eg set up and size accordingly so the unit never gets so excessively discharged. Sizing accordingly is everything with the units, so beware that its almost always necessary to get a designer or heating engineer to do these calculations for you, either that or be scrooge-like with your DHW consumption and phase your energy usage to be in line with PV generation / other low cost heat input etc. Horses for courses there. The incremental price increases per unit, after you've accepted the initial 'hit', are quite reasonable and I always demonstrate the cost uplift to go to the next size unit which many feel is 'worth the money'. I'm an advocate of sizing for the worst case and to have room for storage of all but 100% of any surplus energy, so thats always my recommendation. For eg to uplift from a size 9 unit, in an eHw, to a size 12 unit is an uplift of only £300+vat. Thats a no-brainer AFAIC, given PV production isn't guaranteed every day, so bit of surplus storage is a good idea for when it is. Sizing to get through 24hrs without needing grid top-up / boost is the aim IMO.

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Shouldn't be a problem at all for a properly designed PV diverter.  Any PV diverter that senses true power at the meter tails will work fine, as all that happens is that it will sense the relay opening as a reduction in metered demand, which will then cause it to try to divert more power by leaving its SSR on.  As soon as the Sunamp power relay closes then the diverter should automatically sense the increased demand and start adjusting the on/off cycling of its SSR in order to ensure the maximum level of self-consumption.

 

My PV diverter isn't in any way unique in the way it operates, and it had absolutely no problem in dealing with the start up pulsing from the Sunamp controller.  Having said that, as the start up mode only lasts for ten to fifteen minutes, it makes sense to just switch the PV diverter to bypass mode and apply full power to the Sunamp input.  That will ensure that the start up warming process happens as quickly as possible.

 

From then on it's unlikely that the Sunamp heat cell will cool down to the point where it needs to do a cold start, as this only happens when all the heat has been taken from the cell and the PCM is completely solid.

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The Apollo GEM works just fine in its "variable" and "threshold" modes and will charge the sunamp perfectly well. The only drawback (and it would be the same with other diverters) is the fact that you can't use any form of low temperature override as the sunamps don't have anyway of outputting the current temperature (either flow or stored).

 

So imagine the scenario:

 

You have your solar diverter set to variable (I.e. it will only send excess generation to the sunamps)

Due to high demand (for DHW or UFH or both) the Sunamp(s) become depleted.

However your solar generation is nigh on nil (Cloudy day) so no way they can get out of their "defrost" mode. 

 

The GEM can overcome this problem with a simple temp sensor. In a "normal" scenario this reads the tank temp and when it drops to a pre-determined level it kicks in the override and pulls grid electric. 

 

The solution is pretty simple but not very intelligent; If you think you're going to have high demand then hit the boost button! 

 

My setup is further complicated by the fact that I've got two Sunamps (9kw) and the Apollo and one 16amp circuit is feeding both of them. Something it does by either load sharing or going "1 to 2" or "2 to 1". Again I can solve this problem by presenting two 16amp feeds (hence my other thread). In this scenario you need to use contactors of the GEM channels (the unit has three channels/outputs) to protect the units outputs. 

 

I'm wondering if the above could be achieved by putting a temp sensor on the flow pipework? It certainly drops back considerably once the units start to discharge. 

 

My other frustration is I'd like to be able to tell my GEM to "boost" linked to my other heating controls. I wont get complicated on this thread but my UFH controls (valves, pumps etc) are controlled from my c-bus relays. I cant help think that there must be a way to use a volt free relay to make the GEM believe it needs to boost. But I'm no electronics expert. 

 

One thought I did have was effectively feeding the Sunamps with two 16amp supplies each. One from the GEM diverter and one from my c-bus relays (via contactors). Thus the GEM could just "do its thing" and then if I wanted to boost I could switch on the other supply. I can't really see a reason why this would cause a problem to the Sunamp controller but perhaps @JSHarris has a view?

 

I have to say the GEM is seriously powerful and is probably the most flexible solution I've come across. Its only in the last few days I've started getting my head around its capabilities. 

 

Oh and to keep the thread exciting how about a picture :)

 

20181021_123124635_iOS.thumb.jpg.054e00be2181e0d981449a62a04a42e5.jpg

 

 

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2 hours ago, JSHarris said:

One slight snag with the Sunamp Uniq models that have an electric heating element is that you can't tell whether or not the power relay is on.  I fixed this on mine by adding a 230 VAC neon indicator to the power relay A1 and A2 terminals, with the indicator fitted into one of the spare cable glands on the box.  I can now see at a glance whether the Sunamp is calling for heat or not, which is very useful, IMHO.

 

I need to do this! Have you got a part number or link to the neon you used?

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I can't understand why a PV diverter needs to know the temperature of anything.  Mine only knows about the power flowing into or out of the house supply and needs nothing more to work perfectly.  Others are similar to the way mine works, as I looked at how a few work before building mine, although I haven't heard of the Apollo GEM before now.  The main variation between the different makes available is how they switch excess power to a load (and it can be any load, doesn't have to be a water heater).  Mine uses an energy bucket principle, with bursts of power being zero-crossing switched to the diversion load, others use a variable power switching method, either by using phase control or by using a zero-crossing pulsed control.  None should need anything other than instantaneous power sensing at the meter tails to work properly.

 

I just boost mine by switching out the PV diverter and applying power directly from the supply to the Sunamp.  I have a time switch to do this, in series with a 20 A  switch to isolate the boost function in summer.  Dead easy to wire up and allows the time switch to provide an early morning two hour boost in winter when there's not much PV generation, or a manual boost by pushing the over ride button. 

 

The neon I used came with nice long leads that will easily reach the relay A1 and A2 connections, £1.90 from eBay, including postage.  It's 10mm in diameter so is a nice snug fit in the spare cable gland: https://www.ebay.co.uk/itm/Red-Neon-Indicator-Pilot-Signal-Lamp-AC-220V-w-Cable-UK-Seller/372357642057?hash=item56b23eb749:g:vTAAAOSw7mpbPRpC:rk:1:pf:1

 

 

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13 minutes ago, JSHarris said:

The neon I used came with nice long leads that will easily reach the relay A1 and A2 connections, £1.90 from eBay, including postage.  It's 10mm in diameter so is a nice snug fit in the spare cable gland: https://www.ebay.co.uk/itm/Red-Neon-Indicator-Pilot-Signal-Lamp-AC-220V-w-Cable-UK-Seller/372357642057?hash=item56b23eb749:g:vTAAAOSw7mpbPRpC:rk:1:pf:1

 

Ta! Ordered.

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15 minutes ago, JSHarris said:

I just boost mine by switching out the PV diverter and applying power directly from the supply to the Sunamp.  I have a time switch to do this, in series with a 20 A  switch to isolate the boost function in summer.  Dead easy to wire up and allows the time switch to provide an early morning two hour boost in winter when there's not much PV generation, or a manual boost by pushing the over ride button. 

 

Have you got a photo. I can't get that straight in my mind. 

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45 minutes ago, Barney12 said:

 

Have you got a photo. I can't get that straight in my mind. 

 

This photo isn't that clear and doesn't show that there are four wires coming from the PV diverter into the timer and boost enable switch, an always-on line direct from the 20 A isolator, a switched line from the PV diverter, and a neutral and PE.  The switch in the time switch is connected in series with the boost enable switch below, so timed boost only works when the boost enable switch under the time switch is on.  The timer has an over ride push button that allows a manual boost at any time.

 

329257961_AnnotatedSunampUniQeHWinstallation.thumb.JPG.b3094b0d6ff4172b3c3b8c6be4369a12.JPG

 

The RCBO protected 20 A supply from the consumer unit runs to the 20 A DP isolator, and from there one cable runs to the PV diverter and another runs to the 5 A fused connection unit.  The two cables from the FCU run to the Sunamp control box and the flow switch that controls our preheat pump.  The PV diverter only switches the line conductor on and off, using a 25 A solid state relay.  It's fine to just bypass this solid state relay with the time switch contacts.

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