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Mikey_1980

The Ecocent was switched on Today

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Some of you may remember my other thread from the old site, we have opted for the ecocent maxi for our DHW needs, well today was the day that they started turning everything on, and I waited for the drop in temperature and the realisation that we had made the wrong decision but I am pleased to say so far it all seems to be working well, I asked when he was going to switch it on as I had been out but he pointed out it was already running, the noise was non existent and the two temperarure sensors that I had never changed from the 20 degrees C that the house is at at present. There is no heating in the house the ASHP and MVHR are all being done over the next week but so far so good as all the comments made be worry about the ecocent.

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Hi Mike

We have been pleased with ours in our small cottage. I thought we would have problems with water running out as it is a holiday rental with 6+ people staying most weeks. Been 3 years and we have never had guests complain of water running out. Electricity usage is very low and averaged over the year is about £45 per month for everything as only electricity available

Looking forward  to updates on the MHVR as got my name down for one.

 

Martin

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Thanks Martin, they switched on all the units today (ASHP, MVHR and the Ecocent) with our electrician today and everything worked fine they are back over the course of the next week to clean the UFH loops and refill with water/glycol, adjust the flow rates on the MVHR and hopefully we will be good to go. We are hoping to be in by 2nd July.

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Be interested to see how this goes, as the physics are straightforward; if you take a couple of kW of heat out of a house to heat hot water than somehow that couple of kW has to be replaced, or else the house will cool down. 

The bottom line is that the heat has to come from somewhere, so unless there is "spare" heat coming from somewhere, then additional heat needs to be added to compensate for the heat taken from the house to heat the water.

In a well-insulated, airtight, house, then the effect of taking even 1 kW of heat out is, without a shadow of doubt, noticeable in cold weather.  If I take around 1 kW of heat out by turning on our Genvex in cooling mode it's extremely noticeable in winter, but barely noticeable at all in summer, when there are far lower heat losses and a fair bit of solar gain, even on cloudy days.

I remember discussing this at length with someone who had an Ecocent and his findings were the same, except he had a sun-heated glazed porch that collected heat and, IIRC, an air feed from a workshop with a wood burning stove to supply the additional heat that the Ecocent was removing from the house.  I modelled the performance of using one, with great help from the ESP people, but just couldn't get the sums to add up for our house, with it's low overall energy needs and high sensitivity (especially in cooler weather) to changes of even a few hundred watts in heat input/output.

The flip side is that I know a chap who lives a few miles away, in an older house with wood burning stoves and a Rayburn and the Ecocent works very well (apart from a corroded stainless cylinder - which was something amiss with the protective anode IIRC).  It works well because a couple of kW is a negligible change to his overall heating requirement.

 

 

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It sounds like an Ecocent for summer use (to help cool an overheated house) would be a good thing, and something else for the winter? but that's duplicating equipment so probably not viable.

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I would not expect to see a problem at this time of year when most of us have windows open (or the MVHR is just shifting air and not in recovery mode much).

The test will come in the winter.  But then it may be hard to disaggregate the thermal shift from space heating to DHW regardless of what the electricity monitors say.

The only way to really find out is to run the house with the heating on for a few weeks (so that you get a spread of temperatures) and then do the same with the Ecocent on.

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If I can find it I'll dig out the model I did.  It was a long time ago, as the debate was over on the GBF, so long before we'd pinned down the detail design for this house.

The main summer benefit is the massive increase in ventilation rate if the unit is connected up to an MVHR.  It increases the whole house ventilation rate (in our case) by a factor of four or five, IIRC.  That then massively degrades the MVHR heat exchanger performance and was the major cause of increased winter heat loss.

As you say, not a problem at all in summer, as the air outside is plenty warm enough most of the time, plus there will be solar gain.  I've been surprised this week to find our house hitting 23 deg C (the point where the cooling system kicks in) even when it's only 16 deg C outside and it's heavily overcast.  I measured the outside of the front window frames and they were about 30 deg C, a surprising amount of solar gain given the conditions.

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We had a Nibe EAHP in our last house which operated on the same principle - taking heat from the house to provide hot water.

Our EAHP provided all of the mechanical ventilation so different to the ecocent in that regard, as the amount of air extracted from the house was defined by the ventilation rate.

In summer, or when ambient air temp above 13/14 C the fact that heat was being extracted from the house didn't matter as it was made up by incidental and solar gain. In winter, with insufficient natural gain,  heat had to be added back into the house replacing that extracted for producing DHW.

I think there are applications where an EAHP makes sense, a warm climate out of you have a source of waste / free heat that you can harness. I wouldn't fit one again.

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Any idea on the supplier / cost on the buffer tank ..?? 

It only looks about 50 litre ..?

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It's from Earth Save, 50 litres and I think about £190 on their website but they are doing a full install for us so no real idea of the individual cost.

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If you had a small space heating load, could you put one of these small Ecocents in a garden shed and pipe the warmed water into the house for UFH.

All I would need is about 25 m2 heated.

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You could, but as an experiment you'd probably find buying direct from China will be a lot cheaper and give you some options that are better suited to this application.  These units are extremely popular in China, with seemingly dozens of companies making near-identical units, including the stand-alone ducted air to water heat pump box, which might well be better suited for something like this.

I did a fair bit of research on these years ago, when I was seriously considering using either the Ecocent or the stand-alone heat pump box, and it seems that there are still loads of them available at reasonable prices.  Here's a few of the very many Ecocent-like units:

https://www.alibaba.com/product-detail/Air-source-heat-pump-250l-hot_60365500444.html?spm=a2700.7724857.5.16.k0LV15&s=p

https://www.alibaba.com/product-detail/All-in-one-Heat-Pump-Water_275220833.html?spm=a2700.7724857.29.12.k0LV15&s=p

https://www.alibaba.com/product-detail/Air-ducted-all-in-one-heat_725212021.html?spm=a2700.7724838.0.0.jfQhch

https://www.alibaba.com/product-detail/Alto-AHH-R030-20-quality-certified_60411875790.html?spm=a2700.7724857.29.94.k0LV15

https://www.alibaba.com/product-detail/floor-standing-300L-air-source-heat_60235887069.html?spm=a2700.7724857.29.110.k0LV15

https://www.alibaba.com/product-detail/Air-source-heat-pump-water-heater_673442048.html?spm=a2700.7724857.29.308.k0LV15

and here's a couple of the ducted heat-pump only units:

https://www.alibaba.com/product-detail/Hot-water-heat-pump-with-circulation_1227070644.html?spm=a2700.7724838.0.0.yt9man

https://www.alibaba.com/product-detail/Air-Source-Heat-Pump-Water-Heater_60220362423.html?spm=a2700.7724838.0.0.jfQhch

I found that a few of the Chinese manufacturers were surprisingly helpful, with one even offering to give me a sample of a unit that looked absolutely identical to the original Ecocent (except the label) for just the cost of shipping, if I would review it and write up an English description.  I was more interested in the small ducted air to water heat pump unit, though, as it seemed that it could potentially be more versatile, albeit at a slight loss in efficiency (pretty much all the tank-top fitting units I looked at had a direct refrigerant to tank heat exchanger unit, so don't have a water circulation circuit).

 

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I was thinking of one of the China units.

It just struck me that I very rarely need more than 1 kWh of space heating (and I only have 3kW for DHW anyway), and getting a HP that small is not easy.

I am sure that the units can be hacked to set the default temperature to anything I like (probably no more than 40°C.  As the units are pretty quiet, I would not have to worry about upsetting the neighbours.

Something to research more I think.

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Getting ESP to admit that the Ecocent is really a Chinese imported unit that they have had properly CE tested and stuck their badge on is not easy, but I'm damned sure that's exactly what it is, anyway.  I looked very closely at the original and the Chinese vendor sent me a stack of technical information and photos and it was absolutely identical in every way to the Ecocent.

The snag is that these are all constant power devices, they do not have inverter drive and so are either full or nothing (the same is true of the Ecocent). This means that you have to accept the full power (a couple of kW) and then store it in a buffer to prevent short cycling.  They are pretty well made, at least the data from the Chinese ones I was sent seemed OK, but pretty basic in terms of controls, just a relay control board to switch things one and off, with a conventional motor starter on the compressor, no form of variable speed control.

Temperature setting is easy, the in-duct units have a threshold water flow temperature (just a simple thermostat) and you can set this to anything you want.  Turning it down will probably make the unit short cycle, but with an input power of around 400 to 600 W I'm not sure that's a significant issue.

A better unit for just supplying this sort of output would probably be one of the Spanish/Portuguese direct collector heat pumps, with the plate heat exchanger(s).  There's a dearth of decent information on them, most probably because they were designed for use in a warmer, drier, climate than the UK, and there have been reports of them icing up when used to provide hot water at 50 to 60 deg C here, but I'm fairly sure they could be turned down to a lower temperature and run ice-free.  They have the big advantage of not having a fan on the external heat exchanger, it's just a black anodised aluminium plate affair.

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So one week in and it is working really well, the house is maintaining a constant temp or 21/22 degrees, we have been running the HW to drain the tank and re heat and are seeing now temperature shifts, the noise from the unit is no existent as well, so definitely a good options for the summer months we will have to see what the winter brings, but so far running the water at 52 degreess seems to work really well.  Next week will be the test when we move in.

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Mike 

don't know if you have used the timer function, we did but reverted to running it 24/7 with a temperature drop of 10 deg triggering the switch on. The benefit  is that if showering or having a bath my system extracts through these rooms so to a certain extent recycles the heat lost

Martin

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On 6/16/2016 at 13:40, Mikey_1980 said:

Some of you may remember my other thread from the old site, we have opted for the ecocent maxi for our DHW needs, well today was the day that they started turning everything on, and I waited for the drop in temperature and the realisation that we had made the wrong decision but I am pleased to say so far it all seems to be working well, I asked when he was going to switch it on as I had been out but he pointed out it was already running, the noise was non existent and the two temperarure sensors that I had never changed from the 20 degrees C that the house is at at present. There is no heating in the house the ASHP and MVHR are all being done over the next week but so far so good as all the comments made be worry about the ecocent.

Just to let you know the 200, 300 and 300ltr Maxi are now listed on SAP for DHW and MEV.

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Thanks Himac, yes I am fully aware, we waited for our final EPC until it was on the SAP database, we saw an improvement in both our CO2 emissions as well as the EPC score due to the ecocent, we scored 92 (A) with no Solar PV at all and and ASHP for heating.

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On 10/10/2016 at 16:23, Himac said:

Just to let you know the 200, 300 and 300ltr Maxi are now listed on SAP for DHW and MEV.

Perhaps we could have a bit more meaningful contribution please, rather than just bumping the previous 'information' ;)

The management. 

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This is an old thread.

 

But I was interested reading users discussions of the ecocent and just wondered where people put their heat extraction ducting. The principal place the system is designed for is the bathroom and ensuite to get the recover the heat in the air. But what I am more interested in is where else you could extract heat? I was planning to have a duct running in the roof space and also putting one in our upstairs storage cupboard where our stove pipe will run? The idea being that in the summer the roof space should heat up from the sun on slates and also from our veluxes and in the winter when we light the stove this would get heat coming off the pipe? 

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7 hours ago, Thedreamer said:

This is an old thread.

 

But I was interested reading users discussions of the ecocent and just wondered where people put their heat extraction ducting. The principal place the system is designed for is the bathroom and ensuite to get the recover the heat in the air. But what I am more interested in is where else you could extract heat? I was planning to have a duct running in the roof space and also putting one in our upstairs storage cupboard where our stove pipe will run? The idea being that in the summer the roof space should heat up from the sun on slates and also from our veluxes and in the winter when we light the stove this would get heat coming off the pipe? 

 

 

For a new build, integrating the MVHR and ASHP unit into the same ducting seems the least worst option.  It allows the waste heat from the MVHR exhaust to be further utilised by the small ASHP unit, with the two downsides being that when the hot water is being heated the MVHR runs massively out of balance (by well over a factor of ten) and the house will need to have a heating system that can supply the heat that the small DHW ASHP needs to heat the water.  The latter point depends very much on the house.  When heating hot water one of these units is extracting around 2 kW of heat from the air in the house, no matter how it's ducted.  That's over four times our nominal winter whole house heating requirement, so unless the heating system can put the heat back into the house in winter it has to cool the house down.

 

It's really a matter of scale as to whether this is an issue.  If a house needs an average of around 10 kW of heating to stay warm in winter, then increasing this to 12 kW  for the few hours a day when the DHW heating is running doesn't make a lot of difference; it's only a 20% increase.  However, if the house is like ours, and only needs an average of less than 500 W of heating to stay warm in winter, then that would increase to around 2.5 kW, so a 500% change. 

 

The bottom line is that none of these units give "free" heat, they all extract heat from the house in order to heat the water.  They are efficient in terms of electricity use, without a doubt, but the heat energy they deliver to the water still has to come very largely from the heating system that is keeping the house warm enough in winter.  In summer this isn't an issue, in fact it may well be a benefit in extracting some excess heat from the house.

 

It's worth noting that there are quite a few systems like this, some built into DHW tanks, as is very common in the Far East, some stand alone boxes.  Availability in the UK is pretty much limited to a couple of suppliers, AFAIK.

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