Hybrid heating system

JD6910

hi folks,

anyone out there have any experiences of hybrid heating systems??

what i mean by hybrid is a buffer tank which is primarily heated by solar, a solid fuel stove and topped up by an oil or gas boiler as required.

the theory is that the "free" solar does the hard work by raising the water temp somewhat, the stove contributes when it is on (mainly after 5pm in the evenings and typically all weekend) and if oil or gas boiler is needed then it does the least bit at the end.

any theories on this??????

Latro

If you are lucky with weather solar could only contribute to your heating in summertime but who needs heating at this time of the year.

In the winter they won't even satisfy your hot water needs so I don't see any sense in connecting them to your heating system.

Maybe if you had massive array of them it could work, but that would be as massively expensive and your southern roof area is likely not be enough.

JohnnieK

You also need a large volume buffer around 500/1000 litres. In the winter the solar gain is a lot lower but it still should achieve a temp of around 35oC in the buffer. The stove would heat it no problem and it would be better if you had underfloor heating. I don't know how well this system would work with low temp rads.
There seems to be less rain in the winter now than in the summer months, and rain kills solar panels.

Have a look at the Ariston Nuos as an alternative to your hot water needs.
www.ariston.com/uk/Viewdoc.aspx?co_id=374

Latro

Constant 35oC in 1000L buffer from solar system in the winter not going to happen. Maybe if you don't use it for few days, but you need to pump that hot water every day. As I said solar won't even be enough in the winter to heat your hot water for shower etc so why would you direct that heat into your rads? Also keeping this amount of water hot by backboiler stove is not easy either. You would propably be better off by moving that stove into your garage in form of high efficiency solid fuel boiler and not to worry about big mountain of fuel and ashes that have to go through your livingroom. It's the cheapest option to heat right now but require some every day work like preping your solid fuel and removing the ashes. But you are considering doing it in your livingroom anyway so that shouldn't be a problem. From the garage/boiler room it is also very easy and relatively cheap to implement oil boiler as supplementary heating later on if needed. Sorry for the wall of text. For some reason I cannot edit it.

JD6910

The solar is meant to do just some of the hard work by raising the temp somewhat.the stove then contributes and the balance is done by either oil or gas.

The big question is underfloor heating or rads with the system??????

Thinking of 90 solar tubes.

JohnnieK

JD6910 wrote: »

The solar is meant to do just some of the hard work by raising the temp somewhat.the stove then contributes and the balance is done by either oil or gas.

The big question is underfloor heating or rads with the system??????

Thinking of 90 solar tubes.

I would still favour underfloor heating. Must be designed and installed correctly. Most systems operate around 38oC lovely and low. This will also depend on the coverings on the floor.

Latro

JD6910 wrote: »

The solar is meant to do just some of the hard work by raising the temp somewhat.the stove then contributes and the balance is done by either oil or gas.

The big question is underfloor heating or rads with the system??????

Thinking of 90 solar tubes.

But why would you off load that small bit of your solar energy into your buffer for heating when then you have to heat tap water with something else.

Latro

"The big question is underfloor heating or rads with the system??????" If you are considering solid fuel energy source and 1000l buffer (propably bigger would be smart thing to do) you can go with anything you want, rads or underfloor or mix of both will work great.

JD6910

Latro wrote: »

But why would you off load that small bit of your solar energy into your buffer for heating when then you have to heat tap water with something else.

the solar will heat the domestic hot watrer first and any excess will go into the buffet and be available for heating. i think it is the tank within the tank system. any thoughts???

JD6910

Latro wrote: »

"The big question is underfloor heating or rads with the system??????" If you are considering solid fuel energy source and 1000l buffer (propably bigger would be smart thing to do) you can go with anything you want, rads or underfloor or mix of both will work great.

maybe i am looking at this all wrong because everyone seems to be going for this heating on all day everyday option - but we think we dont want a heating system that is on 24/7/365, even if it on very low. We feel that we want a system that we can turn on when we need it and more importantly turn if OFF when we are at work or away from the house and that the stove which we plan to light every evening after work circa 5pm and the solar gain from all the glass south facing will do the rest.

all our rooms are south facing in a long narrow plan design (passive principles). i cant understand a heating system being on when we all at work - yes the house will be warm when we arrive home (but it can be warm by timing the heating to come at 4pm also!!!) and why cant the solar be working all day and doing abit of the hard work in the buffer tank (for free), we light our stove at 5pm and have the oil or gas come on at say 4pm before we arrive home to take more of the sting out of the rooms. the stove from 5pm until say 11pm will heat the rads so that at 11pm the rooms are nice and warm.

we also have the MHRV system that is delivering fresh semi warm air into rooms AND our insulation and airtightness spec will mean that any heat at all within the house will be kept in the house. 200MM cavity pumped, 200MM floor etc etc...

we are trying to put the money into insulation and airtightness and install a "sensible" heating system that WE control as we feel necessary and not have a system that decides to come on at 2pm during a weekday because the temperatire drops outside and we're all at work!!!!!!!!!!!!

JohnnieK

Maybe you should look into hiring a building services engineer to sit down with you a design a system that would suit your needs bet.

JD6910

JohnnieK wrote: »

Maybe you should look into hiring a building services engineer to sit down with you a design a system that would suit your needs bet.

preety sound advise!!!!

surely this is a relatively straight forward system for any plumber to design??

pache

JD6910 wrote: »

preety sound advise!!!!

surely this is a relatively straight forward system for any plumber to design??

Surely!!:D:D

JohnnieK

JD6910 wrote: »

surely this is a relatively straight forward system for any plumber to design??

They should do.

It takes more energy for a heating system to heat a space that has been off for some time than it does to keep a constant temp in that space.

If the house is going to be as air tight as you say then your heat load will be tiny. What ever you decide make sure it low temperature based as this would be the most cost effective way.

JD6910

JohnnieK wrote: »

They should do.

It takes more energy for a heating system to heat a space that has been off for some time than it does to keep a constant temp in that space.

If the house is going to be as air tight as you say then your heat load will be tiny. What ever you decide make sure it low temperature based as this would be the most cost effective way.

if you had the choice - what would you go for - air to water or the hybrid system???

Outkast_IRE

JD6910 wrote: »

if you had the choice - what would you go for - air to water or the hybrid system???

Bit late weighing in here now, but i have installed and worked on the types of systems your interested in.

I dont like air to water for most irish homes, but for a home thats passive or near passive i think its a viable option but i would strongly advise that you
hire someone such as a building services engineer (maybe your architect could advise) to work out as much as possible the energy demands of your building. This is the only proper way to size the air to water properly.

Also if you do consider air to water that they typically operate at lower temps so it probably wont heat your cylinder fully so you would still need, immersion or oil/gas or stove to do that for you.

I see your comments about the underfloor being on 24/7 previously and how you dont want that. In my opinion thats fine client gets what the client wants, all you would need to do is to install a system with proper controls , and zone every room , give each room its own thermostat linked to the correct motorised valve.

This will give ultimate control , you can set each room temp individually and use this combined with the timer controls to find your own balance.
With underfloor control is key to comfort the more the better.

JD6910

Outkast_IRE wrote: »

Bit late weighing in here now, but i have installed and worked on the types of systems your interested in.

I dont like air to water for most irish homes, but for a home thats passive or near passive i think its a viable option but i would strongly advise that you
hire someone such as a building services engineer (maybe your architect could advise) to work out as much as possible the energy demands of your building. This is the only proper way to size the air to water properly.

Also if you do consider air to water that they typically operate at lower temps so it probably wont heat your cylinder fully so you would still need, immersion or oil/gas or stove to do that for you.

I see your comments about the underfloor being on 24/7 previously and how you dont want that. In my opinion thats fine client gets what the client wants, all you would need to do is to install a system with proper controls , and zone every room , give each room its own thermostat linked to the correct motorised valve.

This will give ultimate control , you can set each room temp individually and use this combined with the timer controls to find your own balance.
With underfloor control is key to comfort the more the better.

never too late with advice!!!! can you explain what controls/setup would be best for us? we would like the option of different temps in difference rooms. for example a bedroom that we are not going to use for the next 2 years - i think that room should be set very very low. what is the lowest temp we can set the air to water system at???

still struggling with the idea that ALL rooms are to be at the same temp even though we are not using them!!!:rolleyes:

can air to water be turned OFF in the summer - take the last few days - nice warm weather - typically what temp would the air to water be at? surely it would be OFF

Outkast_IRE

JD6910 wrote: »

never too late with advice!!!! can you explain what controls/setup would be best for us? we would like the option of different temps in difference rooms. for example a bedroom that we are not going to use for the next 2 years - i think that room should be set very very low. what is the lowest temp we can set the air to water system at???

still struggling with the idea that ALL rooms are to be at the same temp even though we are not using them!!!:rolleyes:

can air to water be turned OFF in the summer - take the last few days - nice warm weather - typically what temp would the air to water be at? surely it would be OFF

Ok as control/setup go i would always advise if you go for underfloor heating

1. Have each room or area as its own zone linked to its own thermostat in each room. This gives you control of the temp in each room, it allows you to have some rooms warmer, some cooler it gives you control.

2. You seem to of said can you set the air to water to a very low temp, different systems of different operating temps, im sure the manufacturer will have a reccomended one , you wont be adjusting this more than likely, you will be using your room stats as your control.

Thats your confusion all rooms dont need to be the same temp, you wont be adjusting the air to water temperature you will be using your room stats to turn on and off the heating to each room/area to reach your desired temperature and then keep it at that temp.

Honestly it sounds like you need help with this, as previously suggested i would reccomend hiring someone to size this system correctly for you.