TerryE

Another DHW / DCW / UFH design

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On 13/03/2017 at 09:44, PeterW said:

I've got the Wilo pump - pure preference being those are now plastic casings and the noise is lower. 

 

I can confirm that the Wilo is a lot quieter than the same size Grundfos.  We have a Grundfos (the newer low energy model) on the UFH, and that pump is in the utility room, downstairs.  On the DHW preheat system I fitted the same size pump, but a Wilo, and it's much quieter; so quiet that it's very hard to hear when it's running.  When the time comes to replace the UFH pump then I'd fit a Wilo, just to reduce the noise (not that the Grundfos is really noisy, it just makes a slight noise that I'd like to get rid of).

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4 hours ago, JSHarris said:

 

I can confirm that the Wilo is a lot quieter than the same size Grundfos.

 

A little knowledge too late :) Still the only ones who might hear the pump will be sitting in the ground-floor toilet. (h is optional).

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14 hours ago, JSHarris said:

I can confirm that the Wilo is a lot quieter than the same size Grundfos. 

 

Too late for you, @TerryE, but for others who might be comparing the two, this is my experience as well.

 

We went for the Wilo-based UFH set from Wunda following probably too much research trying to compare it to the Grundfos equivalent, and I'm amazed at how quiet it is.  Our house doesn't have a lot of background noise, but even in our small plant room it's hard to tell whether it's operating when I have it running at about 40%.

 

If only our Immersun unit were as quiet at full load!

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On 13/03/2017 at 08:05, joe90 said:

Peter, I also will be interested in the low temp blending valve for mine so please report back. Also which pump did you go with as I have to decide which is best?.

 

Right....

 

Wunda aren't able to help here - they only have the smaller one in the 35-65 so I'm trying an alternate source. @joe90 I will order one and see what the score is - I may end up importing these things by the sounds of it !! The other one will get used as the TMV..!

 

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What's a blending valve?

if it's the White thing in my photo then Wunda are talking nonsense as that is from them and I can get it to blend down to 25c with no problem

image.jpg

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30 minutes ago, Calvinmiddle said:

What's a blending valve?

if it's the White thing in my photo then Wunda are talking nonsense as that is from them and I can get it to blend down to 25c with no problem

image.jpg

 

You've got one of the old ones - the new ones are by ESBE for up to 5 ports and don't go lower than 35c

 

Chat with their tech department was interesting as his view was just run at 35c and it will just reach temperature quicker - didn't seem to grasp the concept of not going full chat and over heating.... The whole low energy house thing seemed not to be of interest. 

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1 hour ago, PeterW said:

Chat with their tech department was interesting as his view was just run at 35c and it will just reach temperature quicker - didn't seem to grasp the concept of not going full chat and over heating.... The whole low energy house thing seemed not to be of interest.

 

Peter if this is your problem go back up to my post on @dogman's thread about limiting energy vs. limiting power.  I am replacing the analogue thermometers by DS18B20s.  You could consider doing the same and integrate the  ΔT  (e.g. by sampling every minute and summing).  This will tell you how much heat you've pumped into the slab on this on period.  You can use this to set your mark-space ratio that is heat on to pump recirc ratio where each on period dumps a fixed ΔQ into the slab.  Or you can just replace the TMV and use Jeremy's approach.

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8 hours ago, Calvinmiddle said:

What's a blending valve?

if it's the White thing in my photo then Wunda are talking nonsense as that is from them and I can get it to blend down to 25c with no problem

 

 

That's the same valve and manifold as ours, and it does hold down to 25 deg C OK I've found.  It seems significantly better than an ordinary thermostatic mixer valve in this application, because it remotely senses the internal temperature of the supply manifold, with the capillary probe.  The only downside I've found is that when little power is being drawn from the UFH, that valve shuts right down and presents a fairly high flow resistance to the ASHP, which would cause an over-pressure trip on ours, until I fitted a bypass valve.  Works very well now, though.

Edited by JSHarris

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2 hours ago, JSHarris said:

... until I fitted a bypass valve.  

 

Our ASHP instructions said that fitting of a bypass valve was compulsory.

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With respect to the ESBE valves, WUNDA have selected the ones in the 35-600C range, ESBE also do 20-43oC versions of the VTA322 (valve fitted 5 port manifold) so you could just replace the ESBE valve and then run your manifold at the lower temp.  I have attached the Wunda data sheet M11 Standard ESBE Pumpset.pdf and ESBE VTA320_520_en_E_LR.pdf for the corresponding valves.

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2 hours ago, le-cerveau said:

With respect to the ESBE valves, WUNDA have selected the ones in the 35-600C range, ESBE also do 20-43oC versions of the VTA322 (valve fitted 5 port manifold) so you could just replace the ESBE valve and then run your manifold at the lower temp.  I have attached the Wunda data sheet M11 Standard ESBE Pumpset.pdf and ESBE VTA320_520_en_E_LR.pdf for the corresponding valves.

 

Thats the one I'm trying to source. Initially they told me that it was 30-70c which was ok, but ideally I want the valve operating in its mid range. 

 

The ESBE only fits on the manifold up to 5 ports purely due to the flow rates although I can see that being less of an issue with a lower temperature. 

 

Currently ESBE don't supply anyone in the U.K. with those parts unless you are OEM but I've got one from Poland for £53 delivered so I will see what happens. 

 

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It's a pity that they don't still supply the older valve we have, as it works very well.  I particularly like the way it senses the supply temperature from within a deep pocket inside the supply manifold, as this seems to allow a slightly faster warm up, as the valve opens fully until the supply manifold itself has reached the set point.  It controls well at 25 deg C, which is the number "1" on the dial, but isn't that happy at 24 deg C, and tends to hunt around a bit.  Looking at the valve it seems to be a remote sensor 3/4" thermostatic radiator valve, but there's no obvious manufacturers name I can see now it's installed.

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I have found a supplier who will do a control down to 25 Deg. I am buying most of my equipment from Earthsave products in Wallingford and he showed me their mixer and it covers 25 deg to 60 deg 

http://www.ebay.co.uk/itm/Grundfos-Water-Underfloor-Heating-Manifold-Pump-mixing-valve-unit-/321839526455?hash=item4aef217237:g:KtIAAOSw4HVWDnQU

This one states 35 deg but the can do a 25 deg version

 

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If you can get one of the ones with a 20 deg C to 35 deg C range then I would definitely say that's a better bet.  I have to run ours right on the very edge of it's control range to get a 25 deg C flow, and it's very close to the point where it starts to hunt around a bit, rather than regulate well.  I'm planning to change mine before the next heating season, as I'd like to hold the flow at around 24 deg C if I can.

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Is there an electromechanical option at all? Something I don't believe we've looked at yet, iirc? Or have we?

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1 hour ago, Nickfromwales said:

Is there an electromechanical option at all? Something I don't believe we've looked at yet, iirc? Or have we?

 

Yes, there is.  The head is a standard threaded fit on the valve, so a pulse width modulation capable electrothermal actuator could be fitted, connected to a suitable controller that senses the flow manifold temperature.  Our manifold already has a deep internal pocket screwed into the flow end, so fitting a sensor inside it would be easy enough.  I did think about doing this, but then decided that I didn't want to have something non-standard.  Although, thinking about it, as some electrothermal actuators are designed to work from a pulse width modulated control signal, there may well be an off-the-shelf controller available.

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