newhome Posted October 2, 2018 Share Posted October 2, 2018 I only got to use my UFH for a month at the beginning of the year when @Nickfromwales and @PeterW fixed it for me as it's been switched off for summer ever since. Now that I've switched it back on in 2 rooms I thought I had better try to understand how it operates a bit more. So first questions: On the TS there are 2 cylinder stats. The top one is set to 65C and the bottom one to 45C. When a room calls for heat what determines whether the boiler switches on? The bottom cylinder stat at 45C? And when it gets to 45C the boiler switches off? And if the hot water is switched on I assume the boiler will stay on until the top cylinder stat is at 65C or the time stops? So the cylinder stats are for different purposes and work independently? Last night it took a fair while for the temp to rise from 17C to 20C and the boiler kicked out 37kw over the course of last night and first thing this morning. Maybe I should have expected this the first time the slab has had to heat up this year however .... This morning when I got up it was at 20C and it hasn't dropped at all today so the heating hasn't come on yet tonight which is a good thing I guess. It hasn't been baltic outside today however. Will be interesting to see how much it drops when it's colder. Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 Getting the house 'warmed through' will take a chunk of heat unless youve elected it to do so incrementally ( leaving the stat on and set to the desired temp ). Peter and I set the system to do 'summer / winter modes' where the top stat is the boss if you select DHW only ( aka summer ), and the lower stat is the boss if youve selected space heating ( aka winter ) where you will then also get DHW as a bi-product of the TS being hot. The idea was, fuelled by confusion and free beer, to only heat the upper 1/3rd of the TS during summer ( or when only hot water was required ) to reduce the volume of heated water. As there is far less volume then, the stat is set to a higher temp to get the boiler to kick in sooner, but to also have less work to do ( as at 24kw it was undersized for the system ). The lower stat is set to the lower temp as there is much more water and far less recovery for the boiler to do when the TS is full of warm water. Dont forget that the boiler also has to heat up 450L of cold water when you select the heating and water from a standstill before anything gets to the UFH. Comprendez vouz ? 1 Link to comment Share on other sites More sharing options...
newhome Posted October 2, 2018 Author Share Posted October 2, 2018 12 minutes ago, Nickfromwales said: Comprendez vouz ? Oui, je comprends merci. I had all rooms set to summer until yesterday so the UFH has been off for about 5 months and now I've switched on 2 rooms. So no incremental - just wham bam kick arse, heat room now! It's all or nothing with me . So heating is off as still at 20C but then the hot water came on and top of the tank was 54.7C (still have the little stats in) so the boiler came on and 7kw later shut off at 65C. So all good. And the red blending valves do all the clever stuff re the temp that is delivered to the floor? What magic lets the boiler know whether it's supplying the top of the tank or the bottom? Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 Your Heatmiser system Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 And yes, the red Reliance TMVs each control the temp to the ground and 1st floor Ufh manifolds. Without them the water from the TS would go into the floor and cook Mutt n Jeff 1 Link to comment Share on other sites More sharing options...
newhome Posted October 2, 2018 Author Share Posted October 2, 2018 2 minutes ago, Nickfromwales said: Your Heatmiser system . Tis black magic then! I didn't even think the stats were connected to the boiler? Though they were only connected to the manifolds? Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 Just now, newhome said: . Tis black magic then! I didn't even think the stats were connected to the boiler? Though they were only connected to the manifolds? Yup. And that sends juice to the respective TS stats. If the TS stats are calling then they are what tells the boiler to light, so they boiler is the last to know. 1 Link to comment Share on other sites More sharing options...
newhome Posted October 2, 2018 Author Share Posted October 2, 2018 I think I'd better not give up the day job . So the utility room stat that does the DHW is connected directly to the TS somehow to call for DHW heating rather than via the manifolds? Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 Utility room stat ? You been smoking crack........again ? Thought we got rid of everything there and you selected hot water on the hub in the dining area? Link to comment Share on other sites More sharing options...
PeterW Posted October 2, 2018 Share Posted October 2, 2018 @Nickfromwales it’s the utility room stat that has the DHW programme in it .... just the way the Heatmiser system works. Link to comment Share on other sites More sharing options...
newhome Posted October 2, 2018 Author Share Posted October 2, 2018 8 minutes ago, PeterW said: @Nickfromwales it’s the utility room stat that has the DHW programme in it .... just the way the Heatmiser system works. Glad someone was paying attention during McEwan'sGate. You sure it wasn't you smoking crack @Nickfromwales Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2018 Share Posted October 2, 2018 Thought it was the hub that controlled DHW. ? Little Willy and papa Willy’s domain in fairness. Link to comment Share on other sites More sharing options...
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