Big, cold, expensive house!

Moneysavingdoc

Sorry for the long post and First World problems I know...

We bought a big house this year, 1920s with solid walls, high ceilings and original windows (in the front). 5 bedrooms, detached, EPC E, 2200 sqft.
First thing I did was replace all the bulbs with LEDs. Had a smart meter installed ~ £3/day electricity use - so far so good.

Now the weather is colder...Gas CH throughout. New Valiant ecotec plus 435 system boiler installed by the previous owner and a hot water cylinder. Most of the rads upstairs changed for type-22. 

When you turn the heating on, the boiler roars into life at a cost of £4/hr (i.e 35KW/h + inherent inefficiencies)   :-(

The house is slow to warm up so 5 hours later the temperature is 18c (from 10c) but 20 quid down. Unsurprisingly if it reaches the dialled thermostat temperature and the heating stops the house cools quickly and then it kicks back in full blast.

Do I just need to accept that over winter my energy bills will be ~ £1200/month?

I have insulated the loft, ordered secondary glazing for the front of the house (rear is double glazed) and blocked a couple of draughts. I could use an oil radiator to just heat the living room night (but the kids x2 bedrooms plus mine get very cold without the heating on- and there started to form some damp patches, presumably from condensation, which reversed with the heating back on). I tried lowering the flow temperature from 70c to 55c but the boiler still outputs at 35Kwh (and the radiators don't get as hot so it takes longer to warm up). The CH is zoned upstairs and downstairs. It doesn't seem to matter if heating is activated on 1 floor or both - the boiler outputs at full power. And there is a radiator (without TRV) in a hallway downstairs and towel radiator in the upstairs bathroom which always heat up first whether its upstairs, downstairs or hot water that you want..

I found a video demonstrating how to access the installer mode and limit the power output (e.g from 35kw/h to 25kw/h). Is there any harm in trying to titrate this down so long as the radiators still get hot?

External solid wall insulation looks very expensive for a big house...Although the outside could do with a spruce up. I'll struggle to save up for it with these bills though!

Any suggestions welcome!

Magnitio

See if you can rent a thermal imaging camera; this will highlight where you are losing the most heat.

Do you have bay windows in your house? These can sometimes be very poorly insulated in old houses.

As you have a hot water cylinder, the temperature for the boiler needs to exceed the temperature on the cylinder thermostat, so you probably shouldn't try 55. However, 65 might make the boiler slightly more efficient.

Long term, external insulation and rendering would make a huge difference and will add value to your property.

Alnat1

Our previous house was a 1930s semi with bays to the living room and main bedroom above that were single skinned and had very bad insulation. 

We decided to sacrifice the floor space and straighten the inside front walls, giving us very wide window sills but the void space beneath them was stuffed full of insulation and the house was much warmer. Floor length thermal curtains helped too. We did keep the original windows, with stained glass, for a few years but eventually went with modern double glazing.

If your house has similar, it's a simple way to make quite a big difference.

Moneysavingdoc

Yes, some nice big bay windows! Still waiting for some curtains to arrive!

I will definitely investigate external insulation/rendering (although I don't plan on ever moving so won't directly reap the benefits of value addition!)

ariarnia

Magnitio said:

Do you have bay windows in your house? These can sometimes be very poorly insulated in old houses..

if you do a thick curtain across the bay not in the bay can be cheaper quicker and easier to fit then bother about replacing it. it shouldn't get damper than it would because the curtain wont block all heat and air will still flow just not as much. if you don't like it after you get the more important bits sorted. we did the same with our back door/under stairs off the kitchen area that just sucked heat from the rest of the house. 

FreeBear

Magnitio said: See if you can rent a thermal imaging camera; this will highlight where you are losing the most heat.

Long term, external insulation and rendering would make a huge difference and will add value to your property.

A thermal camera is certainly worth trying to get hold of. Octopus do/did a free hire for their customers. Some councils also have some available for local residents. If you are in Cambridgeshire there is certainly one scheme running.

An incense stick is a handy tool for locating draughts - I'd go round each & every window to see if there is a breeze coming through, particularly around the edges. Check the skirting for additional draughts. Once you know where the cold air is getting in, plug the gaps.

I'm not convinced that external wall insulation is the answer for quite a few properties - The detailing around the roof line, doors, and windows has to be right. If you have bay windows, it can look piggin' ugly. In addition, downpipes need to be moved and window sills extended.

The upper half of my property (late 1920s build) is solid brick wall. Slowly adding insulation on the inside and wrapping round the window reveals to kill cold spots. Done one small bedroom and the landing so far, and early indicators suggest it is well worth the effort. Doing it on a room by room basis means I can do the work myself at a pace that suits me. Helps to keep the costs in check.

[Deleted User]

I found a video demonstrating how to access the installer mode and limit the power output (e.g from 35kw/h to 25kw/h). Is there any harm in trying to titrate this down so long as the radiators still get hot?

Try turning down the boiler flow temperature first. All modern boilers modulate down as the house comes up to temperature. 

Sadly, you cannot overcome basic physics. A home will only reach its set temperature when the heat loss equals the heat entering the property. A smaller boiler may give the impression of saving energy but the boiler will just run for longer. A lower boiler flow temperature will also increase home heat up and boiler run times; however, you would be running the boiler in a more efficient mode and saving energy as a result. 

Olly_J

Moneysavingdoc said:

I found a video demonstrating how to access the installer mode and limit the power output (e.g from 35kw/h to 25kw/h). Is there any harm in trying to titrate this down so long as the radiators still get hot?

This is fine to do, on Valiant boilers its setting D0 from the menu accessed from pressing + & i together.

The best thing is try and work out roughly how many KWh output of radiators you have installed in your house, and depending if you heat water at the same time, add the coil output on, maybe 10kw, then set the D0 number to that and see how it performs. A lot of houses usually only need between 16 and 20kw.

What you also might be finding is that your boiler is cycling at such high power output, and on Valiant there is a anti cycle timer which kicks in each time, which is setting D2, you may need to adjust that downwards if there are long periods between firing.

Default is 20 mins in the chart, which translates to an actual time based on the flow temp you select.

Vaillant Ecotec Boiler Anti-Cycling Time – MyBoiler.com

At 70c that would be 2.5 mins, but at 55 that would equate to 8 mins between firing..there is some trial and error required to find your best setting.

Rattusnorvegicus

Dont forget to apply a rotating fan to the most important radiator. nice air movement helps .

Then when that rooms all warmed up. Unplug and go do other radiators. Its only 30 or 40 watts, and compared to the gas use a bargain to spread heat around faster.

Another trick is like in supermarkets to use a heat wall(the heat thing u feel when u enter that actually isnt there to entice u in but to create an air wall to stop the heat escaping) . I use a tower fan on a platform to blow air past my living room windows (where the cold enters).... it creates an air wall that stops penetration of cold into the living room.

Air can be used many novel ways.People dont consider it can insulate. Many tricks i'm sure i've still to learn.

Magnitio

ariarnia said:

Magnitio said:

Do you have bay windows in your house? These can sometimes be very poorly insulated in old houses..

if you do a thick curtain across the bay not in the bay can be cheaper quicker and easier to fit then bother about replacing it. it shouldn't get damper than it would because the curtain wont block all heat and air will still flow just not as much. if you don't like it after you get the more important bits sorted. we did the same with our back door/under stairs off the kitchen area that just sucked heat from the rest of the house. 

Unless there's a big radiator in the bay window, which often results in a huge amount of heat going straight out of the house. 1920/30's bay windows are often pretty abysmal and the solution for many was to stick big radiators under them.

FreeBear

Deleted_User said: We have some of this (bought it cheap from someone that didn't want it). We haven't used it yet so can't comment on how good it is, but reviews seem good.

It's made for insulating solid walls:

https://www.screwfix.com/p/wallrock-white-thermal-liner-wallpaper-750mm-x-10m/98119

Thermal wall paper is way too thin to provide any worthwhile insulation. Whilst in some places, it is just enough to keep the surface temperature up enough to reduce condensation, it will do nothing to combat heat loss. For a standard 9" solid brick wall, you need around 75mm of Celotex/Kingspan to hit current Building Regulation target. Thermal wallpaper is about 4mm in comparison.