navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: thermomatic K temperatures and pump speeds  (Read 2306 times)
nigrid
Newbie
*
Offline Offline

Posts: 16


« on: October 08, 2012, 08:54:50 PM »

I have an akvatherm thermal store with a thermomatic K and heat it during the summer with immersion (large PV array) for domestic hot water.. (in the winter I have a log boiler and this works fine)

1/ I read that thermomatic K should not be used for domestic hot water.. why is this?
2/ my thermomatic K is set to 60deg, am I right in thinking this temperature should be the lowest possible to help keep stratification?
3/ I have set my domestic hot water thermostat to 50deg, is the temperature difference between the thermomatic K and the thermostat sufficent? (I realise I need to boost this temperture to prevent nasty bugs!)
4/ what speed is best for the pump from thermal store to cylinder? at the moment it is middle speed, but I was wondering abotu going slower also to prevent stratification.

many thanks
Logged
BruceB
Hero Member
*****
Offline Offline

Posts: 1043


« Reply #1 on: October 08, 2012, 09:09:05 PM »

I do not know about 'thermomatic K', but if you have have an akvaterm, then it is a thermal store with domestic hot water coils top and bottom run in series, so as the water that comes out of the taps is only heated as required then there is not really any need to be concerned with 60 degrees and legionella.
Logged
dhaslam
Hero Member
*****
Offline Offline

Posts: 6775



« Reply #2 on: October 09, 2012, 11:06:40 AM »

Question no 4 (transfer pump speed) ,  needs this bit of background from your other thread.

My accumulator tank is outside about 20 meters from the house, I have lagged all exposed pipe work, the water from this runs to my oil heater (this is what we used for DHW in the summer) and then around the house, we have a long house (devon long house sort of thing) and the hot water tank is other end of house. so there is a longish run of DHW but inside the house.

Once you run a pump at any speed it is going to  mix the water temperature in the volume between where the water is pumped from and where the water returns.   When you transfer  heat from the store to the other cylinder the return water should still be fairly warm because the  DHW tank shouldn't   normally be cold except at the bottom.   If the  return water is high up in the store  and hot enough it will reduce the heat loss  from the top of the store.    If  not, hot water from lower down will  heat it.   The main thing is that  you limit the destratification caused by the pump.    It is probably best to use  a high pump speed for the transfer  because this reduces the time  that  the pipes are  hot and losing heat and also it speeds up heat recovery in the DHW cylinder.    The long pipe run should be small diameter to minimize  heat loss from the pipes retained water  and that also  means having maximum pump flow setting.   There will be a loss of temperature along the length of the transfer pipe and it is worth measuring at both ends  to see how much is lost.    It should be within  two or three degrees each way.       
Logged

DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
nigrid
Newbie
*
Offline Offline

Posts: 16


« Reply #3 on: October 09, 2012, 05:28:47 PM »

great advice.. gives me something else to play about with!
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!