Renewable energy heating options for existing house

Kash

Hello! I wasn't sure if this thread should go here or elsewhere, but everyone here seems to know their stuff backwards, so I'm hoping you can share some ideas.

We have a 3 bedroom bungalow, built in the 70s. We are trying to make it as energy efficient as possible, but struggle with keeping it warm.

We got rid of the OFCH and installed a solid-fuel stove. It's great and keeps the room it's in toasty when it is lit. It has a back boiler and also heats the rads. Though the rads have been desludged, pumped and drained and so on (I even paid a professional to do it), they still only heat half way down. I've put heat reflectors on them, and they do take the chill off a room, just don't really warm it. They are here as long as the house, but I've no idea if replacing them would help.

We have double-glazing and after we moved in, we had the attic insulated properly. The same firm were going to add insulation to the wall cavities, but thought it was already done, based on holes drilled in the outside walls (?)

I've been looking into other ways of getting hot water when we don't have the stove lit and ideally any way of generating more heat, or keeping it when we want it.

I have looked at solar panels but found them very confusing, and then came across other things like heat pumps and so on which I didn't even know existed, but most information seems geared towards new builds. I have no idea what would be a good next step for an existing house, what to check etc. so really looking for any guidance at all.

MicktheMan

The best advice is to forget about changing the supply of heat into the house for the time being and concentrate instead on how the heat is being lost from the house.
Think of it like a car going from a to b pulling a large trailer with soft tyres full of heavy concrete blocks. The trailer or the blocks are not needed at a or b. Changing the car engine won't make much difference as the load on the car remains the same. Inflating the trailer tyres, removing the blocks or better still unhitching the trailer altogether will make a massive difference to the performance of the car.
The car is your house, the engine is your boiler and the trailer with blocks is your heat loss.

Kash

Thank you for the analogy
So what else can I do to unhitch the heat-loss trailer?

Our house doesn't have noticeable drafts, the house was built before regulations required vents in rooms, so there is only one we added when we installed the stove.

Is there any way to verify that the cavity wall insulation (installed by the previous owners) was done right?

Calahonda52

Kash wrote: »

Thank you for the analogy
So what else can I do to unhitch the heat-loss trailer?

Our house doesn't have noticeable drafts, the house was built before regulations required vents in rooms, so there is only one we added when we installed the stove.

Is there any way to verify that the cavity wall insulation (installed by the previous owners) was done right?

Thermal imaging done properly will help with that so best left till next winter when you have a good temp differential.

Re
we had the attic insulated properly
How do you know it was done properly

Please describe exactly what was there, what was done and how the attic space is ventilated?
Is the attic converted?

IMhO, the stove is never going to do the business.
What are you burning: wet sticks:D

What is the theoretical output of the stove, split between room and rads.

My guess is the house needs maybe 25kW to heat it......

You might consider getting a blower door test done once you fix all obvious air loss points

Kash

Calahonda52 wrote: »

Re
we had the attic insulated properly
How do you know it was done properly

Please describe exactly what was there, what was done and how the attic space is ventilated?
Is the attic converted?

The attic is not converted. We had the insulation that did exist (a thin layer of DIY fibreglass) replaced by an SEAI approved contractor. I believe it is a layer of rockwool now, but it is over 30 cm deep. There is no noticeable heat transfer from the attic to the rest of the house or vice versa - the attic is cold in winter and sauna like in the summer . As for ventilation up there, I have no idea. I didn't think there was any.

Calahonda52 wrote: »

IMhO, the stove is never going to do the business.
What are you burning: wet sticks:D

What is the theoretical output of the stove, split between room and rads.

Well, they do tend to be dry sticks

There's 3kW heat output to the room, and 10kW heat to the boiler
That's split between radiators in each of the three bedrooms, and a small one in the bathroom.

Calahonda52 wrote: »

You might consider getting a blower door test done once you fix all obvious air loss points

I have no idea what that is, so i'll check it out. I think that's my main problem - I don't know what should be done, or what I can do to get it there.

Calahonda52

So the 10 is for hot water as well so IMO its underpowered for the job, compounded by the existing rads which were sized for inflow temp of maybe 80 degrees C, a number you wont get consistently from burning timber.

As the flow temp drops rad size needs to go up for same output.

Have you considered far-infrared heaters as a supplementary heat source...
When u yanked out the OFCH boiler what happened the HW cylinder?

Now to the attic
replaced by an SEAI approved contractor.
just means he was tax compliant.:D

Can you post some pics of the attic job, including the roof felt as well as a few of the external soffit board

Kash

Calahonda52 wrote: »

So the 10 is for hot water as well so IMO its underpowered for the job, compounded by the existing rads which were sized for inflow temp of maybe 80 degrees C, a number you wont get consistently from burning timber.

As the flow temp drops rad size needs to go up for same output.

Have you considered far-infrared heaters as a supplementary heat source...
When u yanked out the OFCH boiler what happened the HW cylinder?

Now to the attic
replaced by an SEAI approved contractor.
just means he was tax compliant.:D

Can you post some pics of the attic job, including the roof felt as well as a few of the external soffit board

I have looked at infra-red but haven't actually bought any. We're putting in an extension in a few months, and I had them earmarked for that.

Moving on to the bits I am less sure of - forgive me if I have the wrong names for things!

The (disconnected) oil boiler is outside. The Hot Water cylinder is still in the hot-press (at least i think that's what you mean? The big tank?). When we changed to a stove, our plumber added a bigger, pre-insulated cylinder. The stove is linked in to that - once the water in the stove reaches 60 degrees, it circulates and heats the radiators and the tap water. Note, the OFCH was useless - it did a worse job of heating the radiators than the stove does now.

I cannot get into the attic easily since the insulation was fit, as it raised the height by over a foot, so I can't make the jump from the step-ladder any more . Nor do I have any idea what a soffit is, so I will have to wait until hubby gets home for the photos That said, I do trust the guy who installed it, and there was a noticeable improvement in the house after it was installed.

Calahonda52

So are there no immersion heaters in the new cylinder or did you decide not to.

Where did the new cylinder go if the old one was disconnected but left there?

RE the attic, no need to ending life or limb...
re That said, I do trust the guy who installed it, and there was a noticeable improvement in the house after it was installed.

Cant argue with that but may still be room for improvement.

Any mould along where the ceiling meets external walls, especially kitchen bathroom bedrooms

soffit is underside pic here
http://futuraroof.com/flat-roofing-products/fascia-boards/

Re renewables in general, I don't think the payback is there: the key is to reduce energy consumption to a minimum first and then provide energy in the most efficient way possible to meet the minimum.


So whats the plan with the extension, are you disturbing the existing roof line?

Kash

Calahonda52 wrote: »

So are there no immersion heaters in the new cylinder or did you decide not to.

Where did the new cylinder go if the old one was disconnected but left there?

There is no immersion heater on the new tank. I did not even know it was possible to have that and the stove on the tank at the same time! The old cylinder was taken away, the bigger one took its place in the hot press.

Calahonda52 wrote: »

Any mould along where the ceiling meets external walls, especially kitchen bathroom bedrooms

Yes, in all of the above. There are no vents in the bedrooms or the kitchen, and quite a bit of condensation builds up on the windows etc., and we have mould along the top edges of the outside walls (and under the window sill in most of those rooms). I have low energy heaters in the minion's rooms which helps keep mould at bay, and we have since ventilated the bathroom, and we haven't had any new mould there.

Hopefully, this the soffit:

Calahonda52 wrote: »

So whats the plan with the extension, are you disturbing the existing roof line?

We're extending the roof line by just under 1/3, as in, we're going:
from this /

---

\ to this /

---

\

We're adding two rooms and a 2nd bathroom. I was thinking of adding solar panels when we do it as that would give us the hot water we would use in the summer - we don't need it as much in the winter as we tend to have the stove lit.

We're doing our best with what we have, but retrofitting improvements is expensive, and I can't always see the return which makes justifying the expense hard, especially as I don't know which investments will actually make a difference. A warmer house would be a huge return for me. The house is lovely in the summer as we're south facing with big windows which let in loads of heat, but on cooler days, the house can be quite cold (it floats around 14 degrees or so).

MicktheMan

Kash wrote: »

So what else can I do to unhitch the heat-loss trailer?

You have to identify the trailer first, then address the priority issues.
Have you considered having a thorough heat loss survey done which also should cover your mould issues? It might be worthwhile before you spend big on your extension / improvements.

Kash wrote: »

We're doing our best with what we have, but retrofitting improvements is expensive, and I can't always see the return which makes justifying the expense hard, especially as I don't know which investments will actually make a difference. A warmer house would be a huge return for me. The house is lovely in the summer as we're south facing with big windows which let in loads of heat, but on cooler days, the house can be quite cold (it floats around 14 degrees or so).

To get a warmer house, you have two choices;
1. increase the output of the heating system or
2. investigate and address the main heat loss issues.

You started this thread asking about solar panels for your hot water. Using the solar budget to address the reason why your house is regularly at 14 degC would be, imho, the best use of the budget.

Kash

MicktheMan wrote: »

You have to identify the trailer first, then address the priority issues.
Have you considered having a thorough heat loss survey done which also should cover your mould issues?

No, but it seems like a good idea! Have you any advice on where to find a reputable heat loss surveyor, or how much a heat loss survey is likely to cost?

MicktheMan wrote: »

You started this thread asking about solar panels for your hot water.

Not exactly. I started this thread hoping to get guidance on increasing the heat in my home. I knew solar was an option, which was why i mentioned it. But from your posts, and calahonda's, I've learned that solar panels would be putting the cart before the horse (or the heat-loss-trailer before the house-car )

And also, i now know what soffit is

Calahonda52

The soffit looks to be unventilated.
The mould/ ventilation issues need to be addressed as the mould is not good for anyone, especially, what did you call them, minions:D

I will await the pics from attic, in the meantime as you have the extension in your head time for some bedtime reading
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx
Its the best 280 pages of free advice around right now.

To rephrase what MtM is alluding to, you need to invest in the fabric of the house to reduce uncontrolled ventilation which is equal to heat loss and stick to good insulation practice, properly done.

Solar thermal panels for summer water is MADNESS.

You are a long long way from looking at RE kit but if you did venture at looking at them, solar PV, fed into the HW tank just might, repeat, might, make sense.

( I feel the wrath of the boards equivalent of God coming)....

Time to get a pro on board, what part of the planet do you inhabit?

Kash

I inhabit the mountainous regions of East Clare

I will read the Code Of Practice. It's going to have to take a back seat until my exams are over, but I'll get there!

In the meantime, I'm looking into Heat Loss surveys, but there seems to be a vast difference in what they entail. Some of the companies use thermal imaging, others use a door fan (?!) - and while the door fan looked bizarre, i found a video of it in action and it seemed way more exact than the videos of thermal imaging (the windows are colder? No way!) I also spoke to a guy who did a little pre-survey survey over the phone. One thing he seemed sure of though was that the house needed more ventilation to address the mould. While I understand that this is necessary for drying it out, I can't get my head around how that would not make the house colder overall?

Calahonda52

Given that you are a student, the attached is from the post-primary section of the SEAI website:D
http://www.seai.ie/Schools/Post_Primary/Subjects/Physics/Unit_6_-_Heat_Transfer/U-Values/

However it does answer your question re Thermal imaging (TI) and also has some pretty stark numbers on payback.

Interpreting TI data properly is sadly something not always found easily, so it wouldn't be my first option, especially if mula is scarce.

The blower door test is much more meaningful as, especially if localised smoke pencils or similar are used.

If you can see the smoke pass through the fabric of your house and out into that Clare air, thats your money!

The main sources of moisture vapour in domestic dwellings are, in random order.
Occupants, especially at night as its confined to the bedrooms so the effect is more concentrated.
cooking
washing
cloth drying

As the attached link shows
http://www.dpcalc.org
the lower the air temperature in the house the less moisture vapour can be retained in the air so it condenses out, giving rise to mould etc.

I will await the attic pictures but my guess is that cold air is getting in under the insulation at the eaves because it is impossible to properly retro fit rigid or semi rigid insulation in an attic once the roof is on, especially if you have a hip roof.

If you are building the extension, I would budget some mula to include stripping off maybe the bottom 1m of roof tiles/slates all the way around, remove slating battens and the felt and get the insulation fitted properly along the eaves, and at the same time provide for roof space ventilation.

Finally, if you are on an exposed site, then Air tightness is even more critical.

I am signing off here for a while, and unfollowing this thread but will check in later.
Others here are far more knowledgable

Joe 90

Kash wrote: »

I inhabit the mountainous regions of East Clare

I will read the Code Of Practice. It's going to have to take a back seat until my exams are over, but I'll get there!

In the meantime, I'm looking into Heat Loss surveys, but there seems to be a vast difference in what they entail. Some of the companies use thermal imaging, others use a door fan (?!) - and while the door fan looked bizarre, i found a video of it in action and it seemed way more exact than the videos of thermal imaging (the windows are colder? No way!) I also spoke to a guy who did a little pre-survey survey over the phone. One thing he seemed sure of though was that the house needed more ventilation to address the mould. While I understand that this is necessary for drying it out, I can't get my head around how that would not make the house colder overall?

Heat recovery ventilation is what you really need. I fitted a single room unit in a bedroom and it really does work. The unit I used is a Vent Axia Tempra P.

Joe 90

Calahonda52 wrote: »

The soffit looks to be unventilated.
The mould/ ventilation issues need to be addressed as the mould is not good for anyone, especially, what did you call them, minions:D

I will await the pics from attic, in the meantime as you have the extension in your head time for some bedtime reading
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx
Its the best 280 pages of free advice around right now.

To rephrase what MtM is alluding to, you need to invest in the fabric of the house to reduce uncontrolled ventilation which is equal to heat loss and stick to good insulation practice, properly done.

Solar thermal panels for summer water is MADNESS.

You are a long long way from looking at RE kit but if you did venture at looking at them, solar PV, fed into the HW tank just might, repeat, might, make sense.

( I feel the wrath of the boards equivalent of God coming)....

Time to get a pro on board, what part of the planet do you inhabit?

Years ago, when I lived at home in Donegal, people would ask, which is best.meaning cheapest, , col, turf or oil? I would always say inulation and more insulation. The haet you pay for is the haet that warms up the birds outside.

Kash

Joe 90 wrote: »

Heat recovery ventilation is what you really need. I fitted a single room unit in a bedroom and it really does work. The unit I used is a Vent Axia Tempra P.

Again, something I've never even heard of, never mind knowing that I might actually need it. On the google list!

Joe 90

Kash wrote: »

Again, something I've never even heard of, never mind knowing that I might actually need it. On the google list!

It's something that I tripped over and at first thought it was just a con but when I did some digging I decided to try and I'm please with the result.

MicktheMan

Kash wrote: »

Again, something I've never even heard of, never mind knowing that I might actually need it. On the google list!

This (ventilation methods) is just one of the many inter-related items which should be covered in a comprehensive heat loss survey.

Kash

MicktheMan wrote: »

This (ventilation methods) is just one of the many inter-related items which should be covered in a comprehensive heat loss survey.

I would hope so, but you know yourself - if I go in completely clueless, then I run the risk of being told I need to fit flux capacitors to all my internal convertatrons and the like

Kash

The extension went ahead much faster than expected, they're putting up the walls today! So my quest for a warmer house is on hold for the time being, until they are finished. Then I'm fully intending to have that heat-loss survey done, and can go from there.

Thanks for everyone's help.

MicktheMan

Kash wrote: »

The extension went ahead much faster than expected, they're putting up the walls today! So my quest for a warmer house is on hold for the time being, until they are finished. Then I'm fully intending to have that heat-loss survey done, and can go from there.

I'm wondering if you are putting the cart before the horse here. Would it not have made more sense to have had the heat loss survey done before extending?

Out of interest, what will the make-up of the finished wall of the new extension be (from outside to inside)?

Kash

MicktheMan wrote: »

I'm wondering if you are putting the cart before the horse here. Would it not have made more sense to have had the heat loss survey done before extending?

Out of interest, what will the make-up of the finished wall of the new extension be (from outside to inside)?

It may well have, but when I inquired about a heat loss survey, I was advised by 3 separate providers that it would be more effective in the run up to winter, rather than the start of summer. One was wiling to do it before the extension, the other two said it would be better to wait.

As for the walls, theyre not finished yet, but from outside to in, it is solid grey brick, 3-4 fingers width of space, 4-5 fingers width of insulation (a solid yet springy board which is silver on two sides, yellow in the middle) and then another grey brick.

zulutango

What u-value are your new windows going to be?

Any idea what the old ones (in the existng house) might be?

People here have rightly mentioned ventilation and insulation as being the possible culprits, but it's just as likely that you've got windows that are no good at retaining heat. Their ability to maintain heat is determined by the u-value, the lower the better.

Kash

Ooh, good question. I can ask the people installing them for the u-values on the new windows. How would i find out the u-values of the old?

Water John

Some times info is printed on the side in between the tow panes of glass.
If you have any sort of double glazing, that are is not you biggest culprit.

As Calahonda said the space under the eaves is a major offender.
BTW, think of him as he is having an op tomorrow, mentioned on another thread. One of the good guys.

Not sure about heat recovery in an old house. these were designed for very highly sealed buildings.

Kash

Sending him all the best wishes in the world. But he'll fly through it, I'm sure.

zulutango

Water John wrote:

If you have any sort of double glazing, that are is not you biggest culprit.

That's not true. There is some woeful double glazing out there that isn't much better than single glazing. Many people think that as long as they have double glazing there's no more they can do with the windows, but the reality is that poor double glazing can leave about 5 times as much heat through them as a bad, uninsulated wall. Special attention should be given to glazing if heat retention is what you're trying to achieve. In the OP's extension, I would go for the best performing glazing possible (u-value of about 0.6W/m2K) and consider replacing the existing double glazing.

Kash

I had been under the impression that good quality, heavy curtains (and being fastidious about closing them) could offset any heat loss through the windows?

We do have very large windows in the existing house, so I was conscious of them being a potential culprit.

zulutango

When it comes to insulation or windows, u-value is king.

If you have large windows and a high u-value then this is almost certainly your biggest source of heat loss.

Edited to answer your question about curtains, these will very marginally help. Can you take a pic of the windows?

Water John

Accept your point Zul, very true if they have large windows as OP says.
Its just the cost of replacement could be high.