PIV units

[Andy1733]

I don't think you can make comparisons of gas usage unless you record the outside temperature ......

That won't be happening. An AVG is good enough for me

 

[Andy1733]

We used to run our gas boiler on timed thermostats to have 21 deg C morning and evening and then switch off overnight and during the day. In the recent cold spell I read up a bit about condensing boilers and it became apparent that I (and most others) wasnt running my boiler within its condensing range. We had a flow temperature of 60 deg C. I reduced the flow temperature down to 35 deg C and left the heating on 24/7. The net result was a warmer house and less gas usage dropped from 98 kWh per day to 72 kWh per day. During this time of constant on the outside temperature had dropped in the cold spell to -4 degC. It's well worth trying reducing flow temp to enable the boiler run in a more efficient range.

I've reduced the flow rate slightly John but nothing as dramatic as yours.
My. Central heating Max flow rate is 70 degree I've set it at 62 on the 30th dec and not noticed any different ATM. We had a cold snap last night and frosty start so I will give it another week or 2 and if the Mrs doesn't moan I will reduce it down to around 55 degree

Btw John. What temperature are you talking about in your home. I was actually thinking if the AVG usage is around 2kwh per hour after start-up and the outside temperature stays above 0 DegC. Then would it be cheaper to run the heating 24/7 than having it run on a timer.

I've seen loads of YouTube videos debating this and I would say most come out on the times cycle over constant but imo it depends on how much the difference is.
If you can have the heating on 24 hours and it cost under £1 per day more surely this is better for your house and health than not being on. Especially since we're talking about a 3 month period max

 

[johnb2713]

I've reduced the flow rate slightly John but nothing as dramatic as yours.
My. Central heating Max flow rate is 70 degree I've set it at 62 on the 30th dec and not noticed any different ATM. We had a cold snap last night and frosty start so I will give it another week or 2 and if the Mrs doesn't moan I will reduce it down to around 55 degree

Btw John. What temperature are you talking about in your home. I was actually thinking if the AVG usage is around 2kwh per hour after start-up and the outside temperature stays above 0 DegC. Then would it be cheaper to run the heating 24/7 than having it run on a timer.

I've seen loads of YouTube videos debating this and I would say most come out on the times cycle over constant but imo it depends on how much the difference is.
If you can have the heating on 24 hours and it cost under £1 per day more surely this is better for your house and health than not being on. Especially since we're talking about a 3 month period max

I run 21 deg C everywhere including a big conservatory. I was keen to try very low flow temperatures with a view to an air/water heatpump, the flow temperature of the heatpump was generally 50 deg C but running 35 deg C ramps the COP value to above 5 which in turn makes it cheaper than gas even on peak rate.

 

[Andy1733]

Thanks John. I've been reading about the dew rate a condenser boiler works and the max is 55c so I've dropped the figures down to 55 and see how that goes for a week.
The forcast has given a steady 6-10 degree for the next 7 days so should give me decent AVG

 

[binky]

The damp behind the units are a different problem. After 3 weeks the damp wasn't improving so I decided to remove the air brick on the outside. It became quite clear on removing the brick that the cavity was full of rubble, debris and wet sand like material. This was about 4 inches above the top of the airbrick. After removing the rubble from around the airbrick of I pushed my hand upwards I could feel the insulation. I decided to remove every other brick along the damp proof course until I found an acceptable clear cavity.
The total distance I had to remove was about 4 MTR and I removed 4 rubble sacks full of debris. I bricked up the holes and fitted a new damp proof membrane. It's been about a week since I finished this and I've noticed the damp receding.
Strangely when I dry the washing the damp patch looks worst so maybe the cold wet wall is attracting condensation towards it.
I got myself one of those moisture readers mentioned above so I can monitor what's happening and I can see what I can tweek to rectify the problem.

bridging cavities with rubble and other detritrus is always a problem. Might have been wrth fitting some of the slit type vents like these to keep some air movenment in the cavity. https://www.manthorpebp.co.uk/wall-floor-ventilation/weep-vents-–-drainage-and-airflow/weep-vent

 

[Andy1733]

bridging cavities with rubble and other detritrus is always a problem. Might have been wrth fitting some of the slit type vents like these to keep some air movenment in the cavity. https://www.manthorpebp.co.uk/wall-floor-ventilation/weep-vents-–-drainage-and-airflow/weep-vent

Not sure there's any point m8. The other side of the wall is concrete floors. The cavity is filled with insulation and the top vents are no longer usable. Those trickle vents would only be any good if the moisture gets in there and it had a mechanical damp proof course. I'm hoping to keep the moisture out

 

[Joules]

Ow and another thing Ive altered is my heating settings.
I set the programme to run. 530am to 8am at 17 degree.. Then 330pm to 630pm at 17 degree. Then 630pm to 9pm at 19 degree. All other times were 10 degree.

I checked out the octopus app and noticed when the heating kicked in (530am,. 330pm,. 630pm) I was having a large spike in gas usage. This AVG over the 2 week I did this at 9.2kwh of gas per start time. Then would drop down to around 2kwh.
For the above settings I was using approx 65kwh of gas per day.

I then changed the settings to kick in at 530am at 17 degree and hold that till 630pm. Then raise to 19 degree till 9pm...
What has surprised me is the AVG usage is around 72kwh of gas per day for the last 3 weeks..

So basically I'm using only 7kwh of gas per day extra and keeping the heating/house above 17 degree. All day.

Way to go AndyWe have an Atag IC27 Plus condensing boiler with an outside temperature sensor. This boiler uses stepless modulation to automatically adjust the CH return temperature so that it is always in condensing mode with radiators only exceeding 50oC on freezing days. Have you balanced your radiators? This range of boilers is at least 94% efficient in converting gas calorific CV value into useful heat for both CH and hot water. Our Bosch tumble dryer has an inbuilt heat pump that consumes about 800W when drying. The cycle auto adjusts to bring down the running time and is only really used by us for towels. The neat thing about our model is that there is no fluff filter the dryer automatically removes it into the drain water. Impressive work by the way in clearing out the cavity did you use a flexible boroscope to take a peek before you started?

 

[Andy1733]

Way to go AndyWe have an Atag IC27 Plus condensing boiler with an outside temperature sensor. This boiler uses stepless modulation to automatically adjust the CH return temperature so that it is always in condensing mode with radiators only exceeding 50oC on freezing days. Have you balanced your radiators? This range of boilers is at least 94% efficient in converting gas calorific CV value into useful heat for both CH and hot water. Our Bosch tumble dryer has an inbuilt heat pump that consumes about 800W when drying. The cycle auto adjusts to bring down the running time and is only really used by us for towels. The neat thing about our model is that there is no fluff filter the dryer automatically removes it into the drain water. Impressive work by the way in clearing out the cavity did you use a flexible boroscope to take a peek before you started?

I was tempted to buy a scope to have a look but with it being over crimbo i decided to jump in and investigate.. the material wasn't very compacted so was wondering if the cavity installation could have contributed to the problem.

Regarding balancing the rads. I'm running smart valves so their isn't a way of balancing the setup. I was a little concerned over this when I installed them as the box room was always a problem slowing the flow enough to heat the conservatory. Tbh I've not noticed any problems so far
I've got it set up so the box room only heats to approx 17 degC and the heat from downstairs keeps it around this or above.

I'm running a viessman 100 boiler. Tbh I don't know much about it. The gas fitter I use for my property's was raving about it so went with it. The only thing I did notice was my last boiler (combi)max flow rate was 85 degC. This one is 70 degC.

As I mentioned above it's now running at 55c. Hopefully if I can get it to 40 ish then I know in the future a ASHP would work

 

[shaunuk]

I love all the investigations and tests with flow temps and keeping the boiler condensing, we have a new but annoying external oil boiler, all we seem to be able to do is change the nozzle for 18, 22, or 25kw. No modulation here. So my strategy is different.
We keep the stat at about 17 degrees in the middle of the house, And burn wood like crazy to heat the house in an 8kw wood burner. We go through about 30 logs a day but its cheeper than oil. When the outside temp is low, the boiler does come on, usually in the early hours and takes the edge off so we can actually get out of bed. Or if we have been busy and out he house a lot and not feeding the beast with logs.
As we cant modulate the heat output of the boiler, our plan is to let it go full pelt and bring thew house temp up as quick as possible, high flow rate, then when the stat is satisfied it switches off for 3-4 hours until we have lost the heat again.
If a had a modulating gas boiler we would be doing the min flow rate, low modulated output continual method insted.
Hoping to move to an ASHP and standalone HP Cylinder to compliment the solar and battery system this year. Would be good to get off the oil as much as possible, apparently burning dry wood is 4x less co2 than burning oil....

 

[binky]

Not sure there's any point m8. The other side of the wall is concrete floors. The cavity is filled with insulation and the top vents are no longer usable. Those trickle vents would only be any good if the moisture gets in there and it had a mechanical damp proof course. I'm hoping to keep the moisture out

Cavities are meant to keep the inner wall dry via the airgap. Outer wall may leak a little, but also internal damp can penetrate the inner wall which then condenses on the colder outer wall, which is why they have the airvents to allow the cavity to 'breath'. Now if you are running dehumidifiers, then there's much reduced internal damp, but I would be inclined to keep some form of ventilation at the bottom, although I've no idea if they would do much when you have insulation in the cavity. Fitting the wrong type of insulation being a cause of major damp problems in some properties.

 

[Andy1733]

Yea m8. The cavity has full fill insulation so that air gap is non existent. Those trickle vents are for mechanical damp proof where the cavity is breached. Above windows, doors ect. It would need a damp proof membrane to go from the inner leaf to the out leaf for those to work.
When I built an extension on one of my propertys I had a 2 hour conversation with the structural engineer about these vents and others like them. Most of today's vents are unless they are going into new builds. Basically my property was designed to breath and the cavity to be clear. I've had the rock wool type of cavity insulation for 20 ish years without problems. Last year we changed it to the bead and glue type which has almost double the u rating and I've got problems. Maybe the old setup was just under the dew point so didn't notice. Maybe the new insulation has tipped me ott so it's now visible. Maybe it's a combination of the other problem.
I've decided to bit the bullet and have a new roof. Plus new windows and doors. Hopefully the conservatory will be swapped for a extension time permitting in July ish

 

[Joules]

I was tempted to buy a scope to have a look but with it being over crimbo i decided to jump in and investigate.. the material wasn't very compacted so was wondering if the cavity installation could have contributed to the problem.

Regarding balancing the rads. I'm running smart valves so their isn't a way of balancing the setup. I was a little concerned over this when I installed them as the box room was always a problem slowing the flow enough to heat the conservatory. Tbh I've not noticed any problems so far
I've got it set up so the box room only heats to approx 17 degC and the heat from downstairs keeps it around this or above.

I'm running a viessman 100 boiler. Tbh I don't know much about it. The gas fitter I use for my property's was raving about it so went with it. The only thing I did notice was my last boiler (combi)max flow rate was 85 degC. This one is 70 degC.

As I mentioned above it's now running at 55c. Hopefully if I can get it to 40 ish then I know in the future a ASHP would work

The Atag can be installed for separate zoned areas of the house e.g. conservatory or box room as I only use one zone I don't as yet use smart TRV but even with them you need to balance the rads, dummy heads may be available to allow you to do this. Its on my to-do list to have fitted self balancing TRV to do away with the problem once and for all. Your Viessman 100 is an excellent choice of boiler some in the range can modulate down to 2kW but they lack inbuilt flu gas heat recovery which gives Atag the edge. Talk with Viessmann about fitting a weather compensation sensor this will bring down your rad flow temperatures but be warned some family members like their rads to run hot. If the boiler CH flow is running at 70oC then it may not be condensing. Again, talk to Viessmann about this.

 

[Andy1733]

I'm not sure the Atag is any different to the smart TRV and app I'm already using!
That is a zonal set-up as the TRV is individual set-up.

Can you explain how they differ?

 

[Andy1733]

Also the balancing of rads using a dummy head and smart TRV? How does this work?

 

[Andy1733]

Just been reading about the viessman weather compensation sensor. £54. It's a simple case of mounting it on a exterior north facing wall (boiler is on a north facing wall)and connecting to terminal 3 and 4 with bell wire inside the boiler..

 

[Joules]

I'm not sure the Atag is any different to the smart TRV and app I'm already using!
That is a zonal set-up as the TRV is individual set-up.

Can you explain how they differ?

Balancing is about ensuring that the CH supply is shared such that each radiator receives enough flow to generate its rated output prior to using TRV. Its a time consuming laborious business but there is plenty of advice out there on how to do this. Zoning means fitting separate heating feeds to each zone. Placing the room thermostat in the living space means it will be warm whilst other rooms will be cooler even with smart TRV in a single zone system because the boiler has turned off. Multi-zoning keeps the boiler on and CH supply off to the living space whilst allowing it on in other zones that demand heat. If you are saying that each of your smart TRV controls the boiler allowing it to be turned on then that's another matter as a time-temperature schedule would be required for each smart TRV for efficient running. Is this what you have?

 

[Andy1733]

Yes m8. On the app you can set individual TRV to be on, off, and at required temp.
upto 8 different temp settings per day. Even if the main thermostat turns the boiler off I can still switch individual rads on to get heat.
You still have a central stat that controls via the room not on a rad but that is for the additional setting not just control.

 

[Andy1733]

Check out the link. The home user explained the product perfectly

 

[Joules]

Yes m8. On the app you can set individual TRV to be on, off, and at required temp.
upto 8 different temp settings per day. Even if the main thermostat turns the boiler off I can still switch individual rads on to get heat.
You still have a central stat that controls via the room not on a rad but that is for the additional setting not just control.

Okay! Any smart TRV can start the boiler as though it was a thermostat is that right?

 

[Andy1733]

I'm not sure if all smart valves can but yes, the ones I have have zonal ability