trying to find an answer for modulation

AbsentMinds

Hi people

This is my first post so go easy and im sorry if this has been asked before. I upgraded my Tado setup to opentherm, i've read all about turning down a condensing boilers flow down to save a bit. My question is, is it better now having modulation to set the flow temp to max or high temp and let tado make the choice on the flow temp?

BOG73

Hi! I am using opentherm for the last 2 years and in my case was better to leave the max flow at 80C,cycling was less present using max flow at 80c. I use to keep it at 60C but my boiler had too many cycling periods. I guess you have to let Tado few days to learn how fast your home Is heating up,maibe you will get mad to see at the beginning how Tado set the flow at 70C but after 10 min will drop at 50C if the thermostat begins to rise. Also,do not close too much the return valves,maibe only the ones closest to the boiler,use 1/2 turn for the first rad or just 3/4(hear the flow🦻)and a bit more for the next rad and so on,the last rad should be near to max open. My system is set to max now but rarely I see a flow higher then 52C and only if the difference between the set temp and actual temp is lower then 1C . I hope it will help you.

AbsentMinds

I see that's good info. I wasn't sure, i tried running at a lower flow temp with opentherm but found it took ages to heat up the house as i have a 1960s house which isnt the best insulated but nor the worst and also the rads are probably slightly smaller to run to low anyway. I know its about finding the right balance but then started thinking if Tado can set the flow it needs, maybe running higher would be better as it might blast hotter to begin with but then ramps it down instead it being 100% at 60 for a long period because it takes so long to get to temp.

AbsentMinds

@BOG73 do you have your heating on a schedule or do you set it at a temp and leave it, i have tried both but unsure which is better for me as the price of gas is so high. What would be a good time period to test this looking at meter reading for?

johnnyp78

Unless you have weather compensation, I don’t see any way that leaving a constant temperature on rather than setting a schedule won’t cost you way more. Surely there are times when you’d prefer the house to be cooler. Overnight for example.

AbsentMinds

@johnnyp78 hi sorry maybe i'm not making my self all that clear. I should of said through out the day, of a night bring it down a bit.

The trouble I'm having is way too much info from looking online and not sure what way to proceed as there are so many different opinions, i use to have a normal setup on/off with a combi but wanted to upgrade and picked Tado. After fitting that then realized it wasn't opentherm compatible as Tado removed it from the uk and after watching vids and stuff online it seemed like it would be good to have. So i bought the EU receiver to be able to run in opentherm.

I've seen so much info on turning down my boiler to condense more is a good thing but found in the winter it took ages for my house to heat or get to temp, but now i have opentherm where it can control the flow rate to what it needs i was questioning if i should set the flow to max and let Tado choose what it needs as setting the lower flow rate with opentherm still took ages.

My second question was am i better off setting a temp for my heating to say 19 of a morning and leaving it as that till say 8pm and then set it lower to 16/17 of a night, as I'm using opentherm and it can keep the temp at 19 without over shooting, I'm not sure if its better than 19 from 6-8am then 17 9-5pm then 19 5-8pm as this might use more gas to get back to 19?

Thanks for the comments and the help

Montage

There is no single answer to this question. The heating system (not just the controller), the property heat loss, the property layout and orientation and whether you want comfort or efficiency will all affect the answer.

Lower flow temperatures restrict the amount of heat you can input into the home. This must affect the rate at which you can increase temperatures.

Keeping temperatures up all day would usually cost more.

Allowing OT to potentially use a higher flow temp when needed makes sense. This will help the system get you back up to temperature in a shorter time (which you seem to want).

People vary somewhat too. A quick read on here shows that.

Just some (necessarily) general thoughts.

AbsentMinds

@Montage hi
Yeah I’ve come to that conclusion, I haven’t invested in them yet but I’m hoping adding some of the Tado trvs will also help, also doesn’t help we are decorating our house too so gaps for air to leeks and drafts.

Well thanks for everyone’s help and I will be sure to come back if I have any more questions for people here.

mindstorm

I'm in a 1920's house with solid walls (although upstairs has now been externally insulated).

I set the boiler maximum to 60deg and let the modulation do the work. Most of the time the boiler is modulating in the mid 30's and it keeps what we now know to be the coldest room at the set temp. I guess the boiler is running 50% of the time in the coldest months to do this.

The heating has never been quick to warm up so I allow for that in my start times.

I vary my room temps according to how much time I spend in the room but I do have 7 SRT. Lounge only heats up from 6pm but having lowered the room temps to around 16-17 over last winter we now use 16000kwh annually instead of 24000 a few years ago.

AbsentMinds

@mindstorm hi

Thanks for the info its good to know, 1 thing that blew me away was your usage. You say you use 16000kwh... mines like 5500kwh annually.... i thought mine was high, but saying that all our cooking is electric as the Mrs wanted integrated stuff instead of gas

mindstorm

Just goes to show the difference in insulation levels over recent years. We don't use a lot of energy for cooking either so most of this is heating input. The only benefit was in the heat last year, the stone floor kept the house cooler 🙄

BOG73

@AbsentMinds yes,i do have my heating on schedule,now the weather is warmer comparing to Nov-Feb period and i scheduled Tado to start every 6 hours(your choice to set when) and leave it on for 45 min,after that 6 hours i"ve set it to 1.5 C bellow my desired temp at the time when Tado start. In colder periods i've set it to start much often,like every 2 hours during the day and hours in the night. I have avoided to let the house to cool lower then 2-2.5C of my comfort temperature,unless I leave the house for a longer period. In my experience,if I stop the heat for too long in colder periods then the house will need more energy(gas) to heat up,the boiler will need to start more often,try to find the balance between the temp you want inside your house,how insulated your house is and how much you pay for gas. I have invested in new windows(triple glazing since 2020) and also i have added insulation in the loft(about 30 inches of mineral wool 2021) and I can say my gas consumption for heat has lowered with 40%. The cost was high and maibe will pay back in 5 years but if i was using that money for a Bmw or another car,in 5 years i will loose that investment..

AbsentMinds

@BOG73 thanks for the info, i have mine set up to come on to 19 in the morning just to take the chill off for about 2 hours and then again at 5pm till 9 but it only kicks in late as the weather is warmer. I did leave it on 19 the other day to see how it would be and it came on a couple of times at a low heat, to top it up and then was off again but again the weather is warmer. Maybe worth me trying it that way for a week and see if it uses less gas instead of it dropping lower at night and then taking the time to get to temp in the morning.

Thanks for taking the time to reply to me dude and @mindstorm as its really helpful as most of the time i read about people with new build houses which is always going to be better in terms of heating so its hard to get a idea of direction i should be heading