That is the setting to let the boiler sort out its own output level.; which in the absence of proper calculations and system design is the next best thing.
UFH New Boiler
- Thread starter swanny65
- Start date
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You can set the maximum power output of your boiler in the d0 setting. It enables the boiler to operate a little more efficiently while heating the system up from cold. But when driving UFH at a flow temperature of 55 C its going to be operating at about maximum efficiency anyway.
But with UFH its really going to make little difference as that only happens once a day ( if set correctly ).
Let me try to explain this! Your house if heated loses about 18 kW of heat all day long. The boiler feeds this heat loss and needs 24 x 18 kWh wne left on all day!
If you turn off the heating at night for say 7 hours then the heat loss is only 17 x 18 kWh .
Some people seem to find it hard to understand this!
Tony
A
ALEC1
More twaddle from agile... The lower the flow temperature the lower the return temperature and the lower the flue temperature and the higher the boiler efficiency..
The skill then is to design a system that operates at the lowest possible temp as much as possible..
This cannot be done withou seperating the DHW reheat from the Heating demand, or with manual mixing valves that blend the heating water temperature down from an unecessarily high flow temperature
The skill then is to design a system that operates at the lowest possible temp as much as possible..
This cannot be done withou seperating the DHW reheat from the Heating demand, or with manual mixing valves that blend the heating water temperature down from an unecessarily high flow temperature
The funny thing is I can see what agile is getting at.
I need DWH only 6 hrs a day but I need UFH 18 - 24 hrs a day. Surely it therefore wiser to have the boiler set up for that that needs it most often, the UFH, and take it that the DHW will not be efficiently supplied by the boiler.
No doubt someone will tell me that is far to simplistic !
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A
ALEC1
the hot water cylinder should reheat from cold in about 40 minutes...it follows then that how long the boiler needs to produce heat is at high temperature for domestic hot water is a function of how much hot water you use.
in reality hot water mode is probably less than an hour a day for most people, thats when the boiler needs to produce a lot of heat.
the rest of the time the boiler can operate at the lowest temperature possible to maintain the house at temperature..
in reality hot water mode is probably less than an hour a day for most people, thats when the boiler needs to produce a lot of heat.
the rest of the time the boiler can operate at the lowest temperature possible to maintain the house at temperature..
To get proper hot water you need a control system which raises the boiler output temperature during water reheat times. Thast usually less than 40 min a day and ideally should be times to be when heating is not needed. Although the long time constant of the UFH means a short time without heat input is rarely noticed.
It should be common sense that heating the house all day is going to be more expensive that only heating it for the 17 hours when its needed ! Odd that some cannot understand that!
Tony
It should be common sense that heating the house all day is going to be more expensive that only heating it for the 17 hours when its needed ! Odd that some cannot understand that!
Tony
A
ALEC1
if you don want to pay for heating dont use it...
The long heat up time of UFH means there is probaly little benefit in short time periods..
The long heat up time of UFH means there is probaly little benefit in short time periods..
UFH on 16 hrs and off 8 hrs can not really be classified as a short time period. I would get this point if the UFH was on 6 hrs in the morning, off 4 hrs until late afternoon, then back on for 5 or 6 hrs in the evening and off the remaining 8 hrs overnight. Lots of energy required to get the UFH up to required temperature twice a day.....
I have been taking regular gas readings and will post the results in due course. Going to run for 2 or 3 weeks permanently on and then 2 or 3 weeks on 04.00 to 21.00 and off 21.00 to 04.00.
A
ALEC1
In this industry there are lots of ons...the boiler, the controller the room thermostat, the boiler thermostat..and yhen yhere ate degrees of comfort too
Your test will be interesting..
Your test will be interesting..
Well of course there is, but the warming up energy is balanced out by the cooling down. Nothing is lost there. Its just a timing shift.
Tony
if you turn your underfloor off for more than 6 to 8 hours you will end up with too much heat being put in to the underfloor creating an overshoot in temp followed by an undershoot.
The very best way with underfloor is to leave it on 24/7 and allow it to control it's demand itself.
If the noise of the underfloor is a problem then leave it off for a max of 6 or 7 hours at night.
Best solution for your setup would be to have weather comp so you can re heat your cylinder at a higher flow temp and then the system use the lowest flow temp for the heating demand as this is where you have the best chance to reduce gas consumption but still have the best comfort.
On smaller and lower gas usage systems i wouldn't bother with the expense of the weather comp but with your gas consumption it would be worth it.
The very best way with underfloor is to leave it on 24/7 and allow it to control it's demand itself.
If the noise of the underfloor is a problem then leave it off for a max of 6 or 7 hours at night.
Best solution for your setup would be to have weather comp so you can re heat your cylinder at a higher flow temp and then the system use the lowest flow temp for the heating demand as this is where you have the best chance to reduce gas consumption but still have the best comfort.
On smaller and lower gas usage systems i wouldn't bother with the expense of the weather comp but with your gas consumption it would be worth it.
I would say that its most important with UFH to have WC as there is no room temp feedback as with conventional stat control.
Otherwise the overshoot will create a too high temp and waste heat as well as being uncomfortable.
Another and perhaps better solution is to have a setback lower circulating temp at night. Common controls do not support that, although its easy to DIY by adding different resistors to the controlling sensors under control of a timeclock.
Tony
Otherwise the overshoot will create a too high temp and waste heat as well as being uncomfortable.
Another and perhaps better solution is to have a setback lower circulating temp at night. Common controls do not support that, although its easy to DIY by adding different resistors to the controlling sensors under control of a timeclock.
Tony
I have been monitoring my usage since 23/12/12 (reading 14396.701) until tonight (reading 14579.101) using a cost estimator from this website http://www.ukpower.co.uk/tools/ my cost per day over this period on 24/7 is £3.48 inc VAT.
However the last few weeks have been relatively mild so I will have 1 further week on 24/7, as we are having a cold snap, and then operate on 16 or 17 hrs a day.
Personally £3.50 a day for the floor area I have, also cooking with gas, seems pretty good. I have a chalet bungalow with a 90m2 ground floor area with second floor above and an additional 48m2 single storey extension.
More readings to follow
Not sure where you're going with that Tony, usually each actuator is controlled by a separate roomstat giving better control not less???
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