renewable heating

mr.stonewall

hi to all

just planning a self build at the moment and trying to figure out the best way to heat the home. we want underfloor and will be on a budget. would like to use log (since we would have a supply Variable) and wood pellet to supply the heating needs and the domestic hot water. the list and price tags of the various options are mind boggling.

thanks

claredearg

We were hoping to do something similar i.e. underfloor heating run on a log stove and solar panels. Does anyone have such a system in place or any advice to offer? thanks

Carlow52

OP1 and and OP2

general
The starting point should be to insulate/airtight the build to the highest possible standard from a cost perspective.

This then allows you arrive at an energy [heat/HW] requirement for the house and u can then look at ways of delivering this.

I hope you have not started with the notion of UFH and work from that:)

Specific

I am not convinced that UFHF works best with a log fire due to the high output temp of the water

GoneShootin

Carlow52 wrote: »

I am not convinced that UFHF works best with a log fire due to the high output temp of the water

My plumber was only saying the same thing to me the other day. UFH likes to run at much lower temps than would be required for rads so linking the stove into the system could prove difficult to manage properly for UFH

sinnerboy

That's what controls and valves are for - mixing heated water with cold to reduce temps as required .

Carlow52

sinnerboy wrote: »

That's what controls and valves are for - mixing heated water with cold to reduce temps as required .

For example to see what thermostatic mixer vales look like there are some in Woodies in Swords

claredearg

We've decided to go with the underfloor, run off the stove with oil as a back up. It seems that everything is in the hands of the plumber, a good one and we're sorted and if we get a bad one, we'll be paying for it for ever more it seems! If anyone can suggest any good plumbers in the Cork area used to installing such a system, that would be great
thanks

gears

claredearg wrote: »

We've decided to go with the underfloor, run off the stove with oil as a back up. It seems that everything is in the hands of the plumber, a good one and we're sorted and if we get a bad one, we'll be paying for it for ever more it seems! If anyone can suggest any good plumbers in the Cork area used to installing such a system, that would be great
thanks

Just one point on underfloor and stoves. To get good performance from underfloor heating the heat needs to be supplied to the floor hours before you actually need to heat the room. So if you need heat at, say 8-9am you would need to be up a 5-6am to light the stove same for the evening you want heat at, say 6pm when you arrive in from work, will some one be there during the day to light the stove at 3-4pm.
I have underfloor heating and it was installed approx 7 years ago and what I've found is that the controls are the most important aspect of the system. I've used Danfos TP5 thermostats which allow for different time and temperature settings over the course of the day which means you can programme your needs into the system and just forget it.
Personally I believe that underfloor will only work well with a boiler (and/or a solar top up if you wish) and proper thermostats where all functions are controlled by time and temperature.

sinnerboy

Very good advice gears .

to others - watch out for 1 potential banana skin . Open plan tiled kitchen leading to dining area with timber floor . even when the system works perfectly i.e. both spaces are heated to the same temp . - you can be "tricked" by your senses into believing that the UFH under the timber is under performing - because by comparison the tiles simply feel hotter .

Make sure to create a separate zone i.e. separate controller for the kitchen and for the dining . You can do a little trial and error to make it feel right - if you only have 1 controller for the kitchen/dining - you can't

GoneShootin

claredearg wrote: »

We've decided to go with the underfloor, run off the stove with oil as a back up.

Try that config only swapped around. Run the UFH off the oil to get it running, then let the stove take over when you've the stove going. As sinner suggested you will need mixer controls. I'd be very slow in having a stove as your primary water heater for underfloor.

gears

sinnerboy wrote: »

Very good advice gears .

to others - watch out for 1 potential banana skin . Open plan tiled kitchen leading to dining area with timber floor . even when the system works perfectly i.e. both spaces are heated to the same temp . - you can be "tricked" by your senses into believing that the UFH under the timber is under performing - because by comparison the tiles simply feel hotter .

Make sure to create a separate zone i.e. separate controller for the kitchen and for the dining . You can do a little trial and error to make it feel right - if you only have 1 controller for the kitchen/dining - you can't

Thanks sinnerboy;)

I have to agree with you on the open plan set up. I have exactly what you mentioned and yes it has always felt a little colder but what can you do, drag out a kango and re-plumb..... Hmmm maybe not

I do have a bit of a mad idea, involving a stove, improved air-tightness, insulation and a HRV which I'm hoping will improve things across the house, but thats' best left for another post.

Carlow52

gears wrote: »

Thanks sinnerboy;)

I do have a bit of a mad idea, involving a stove, improved air-tightness, insulation and a HRV which I'm hoping will improve things across the house, but thats' best left for another post.

Why not now: taking the awesome amt of hot air produced by the stove through the HRV and sent heated air elsewhere in house, looking at that myself at present with the possibility of feeding air for stove directly into it it a closed air feed

GoneShootin

Carlow52 wrote: »

Why not now: taking the awesome amt of hot air produced by the stove through the HRV and sent heated air elsewhere in house, looking at that myself at present with the possibility of feeding air for stove directly into it it a closed air feed

Oh great - another heating option for me to consider. Doubt the cost would be worth it given stove usage is linked to the seasons?

The more I circle around all the different options the more I keep coming back to keeping the damn thing simple

1 Insulate the hell out of the house
2 Some degree of decent air tightness (dont go 100% as I'd like some kind of natural ventilation??)
3 Oil/Solar/Stove/Zoned Rads+TRV

Poor Uncle Tom

claredearg wrote: »

We've decided to go with the underfloor, run off the stove with oil as a back up....

Just interested to know, what thickness of screed will the UFH pipes be in?

sinnerboy

GoneShootin wrote: »

1 Insulate the hell out of the house
2 Some degree of decent air tightness (dont go 100% as I'd like some kind of natural ventilation??)
3 Oil/Solar/Stove/Zoned Rads+TRV

1. Of course

2. go for the max you can and HRV

3. If you do 1 +2 properly you will need very little , possibly NONE of 3

read carefully

http://www.sei.ie/Renewables/Solar_Energy/Low_Energy_Buyer's_Guide.pdf

http://www.sei.ie/Renewables/Renewable_Energy_for_the_Homeowner/SEI_Passive_House_A4.pdf

It is possible to eliminate the need for space heating altogether, and for hot water rely on solar panels for most of the year with only a very small boiler during winter

PeteHeat

Hi,

One of the most important parts for an UFH system is a buffer / thermal store regardless of the type of boiler / fuel being used.

For example a room facing north will usually require more heat than the rooms with a southerly aspect, when the temperature drops in each room it calls for heat and should be able to get the heat when called for not when the timer says it can have it.

The flow temp for UFH is usually between 30 and 40 degrees so why fire a boiler that is producing 60 degrees only to cycle on / off or use a timer which by the time the boiler comes on a concrete radiator of maybe 2,000 sq feet is looking for heat ?

The buffer store can be used with a combination of heat sources, stove, oil, wood, or pellet boiler even add solar.

The temperature can be up to 85 degrees, a mixing valve can be used to control the flow temperature to 60 degrees, the UFH manifold uses a mixing valve to reduce the temperature to the required flow temperature for the system.

All heat requirements for the house can be taken from the buffer, UFH, radiators (often fitted upstairs) and even a coil in the hot water cylinder.

When the north facing rooms call for heat they are getting the heat from a source that is constant, no need to light a stove or fire a boiler for every room in the house.

The major advantage is the temperature in each room is constantly kept at the desired temperature, some of the biggest complaints with UFH is it can take too long to heat the rooms or the rooms get too hot.

The technology is available to heat a home to the customers prefered level of heat, it can be done in a cost efficient and environmentally friendly way.