what type of heating and hot water system?

Simonomis

Hi all,

First time posting to this excellent site!

My wife and I are renovating an old cottage and we are at the stage of installing the heating and hot water system.

I have been researching what type of system to install based on the following requirements:

• Well fed water
• Multi-fuel stove as the main source of heat
• back-up oil boiler
• There is enough space for a medium size cold water/expansion tank but it would be roughly the same height as the shower head in the bathroom (we have extended into the loft space)
• Hot water cylinder needs to be situated down stairs (same level as the stove)
• Would like to choose between the stove OR oil boiler to heat the hot water and supply radiators

Id say this was a fairly standard set of requirements for rural Ireland?

What I do know: Pressurised (un-vented) system is out of the question because of the solid fuel stove. So options are a vented system or thermal store.

Id quite like to install a vented system but I am concerned that the cold water tank would not be high enough to provide adequate head - I think I can install a pump to the hot water system but is it a problem that the cold water tank would be the same height as the shower head? Also there wouldn't be enough space for a cold water tank and a header tank for the stove.

Would anybody recommend a 2014 thermal store system? would I have the the same concerns about cold water tanks and header tanks?

Lastly is anybody aware of some good heating and hot water diagram on-line resources (applicable for Ireland)

Thank you in advance

shane0007

It sounds like you might have no option but to install a pressurised hot water system, that is, if you require getting wet in the shower :-)

An option would seal the heating system, pressurise the hot water system, & install a Firebird heat exchanger to keep the solid fuel vented & to marry the two systems. You can then also fully zone the system from the oil side.

Simonomis

shane0007 - thank you just the sort ideas I was looking for - I had a look on the Firebird site - the Firebird heat exchanger is the first option ive seen for marrying stove with pressurised system - before now all ive read is that you cant do it!

Thanks again

TPM

shane0007 wrote: »

It sounds like you might have no option but to install a pressurised hot water system, that is, if you require getting wet in the shower :-)

An option would seal the heating system, pressurise the hot water system, & install a Firebird heat exchanger to keep the solid fuel vented & to marry the two systems. You can then also fully zone the system from the oil side.

have you ever installed one shane, i have heard a good bit about them but never seen one in operation

shane0007

TPM wrote: »

have you ever installed one shane, i have heard a good bit about them but never seen one in operation

Yes installed a few. They work a treat. Done a system that had an old Stanley oil cooker which couldn't heat the rads & a back boiler that was equally as bad. System done nothing but pitch & was so sludged up, they were burning oil to heat the top rail of the rads only.
They had spent fortunes on various plumbers over the years who added additional vents, a whole warehouse full of non-return valves & never sorted any part of the system.

Now they are nice & toasty with the smallest of fires & the Stanley hops every rad off the wall. The only time I hear from them is when they give my number to somebody, and that's my favourite sort of call back!

Simonomis

Hi all,

I just had a plumber around to discuss the situation - his solution would be to have a pressurised hot water system and a vented stove heating system (indirectly heating the hot water) im guessing much like the image below (but with the hot water pressurised):

I have enough room for a header tank for the stove - question though is this configuration safe?

vented heating.jpg

thanks again

shane0007

Simonomis wrote: »

Hi all,

I just had a plumber around to discuss the situation - his solution would be to have a pressurised hot water system and a vented stove heating system (indirectly heating the hot water) im guessing much like the image below (but with the hot water pressurised):

I have enough room for a header tank for the stove - question though is this configuration safe?

vented heating.jpg

thanks again

Noooooo!!!
Absolute bomb. You cannot install an uncontrollable heat source (solid fuel) into a pressurised domestic hot water cylinder. Absolutely no way. If the plumber suggested this, he knows nothing about pressurised hot water systems.

You cannot raise the cylinder temperature above 65C for pressurised, which the cylinder safety stat is set to. The next tier of safety is 85C and the final safety tier is the temperature relief valve will discharge at 95C.

The cylinder stat must be interlocked with the heat source, whether it be solar, oil boiler, gas boiler, whatever, but it cannot be wired to a back boiler.

Hence, I suggested the Firebird heat exchanger. The pressurised side of this can be interlocked with th second circulating pump, thus providing the fail safe.

Simonomis

shane0007 wrote: »

Noooooo!!!
Absolute bomb. You cannot install an uncontrollable heat source (solid fuel) into a pressurised domestic hot water cylinder. Absolutely no way. If the plumber suggested this, he knows nothing about pressurised hot water systems.

You cannot raise the cylinder temperature above 65C for pressurised, which the cylinder safety stat is set to. The next tier of safety is 85C and the final safety tier is the temperature relief valve will discharge at 95C.

The cylinder stat must be interlocked with the heat source, whether it be solar, oil boiler, gas boiler, whatever, but it cannot be wired to a back boiler.

Hence, I suggested the Firebird heat exchanger. The pressurised side of this can be interlocked with th second circulating pump, thus providing the fail safe.

Hi Shane007,

Thank you - thats what I was worried about! I think the Firebird heat exchanger is number one choice but if you dont mind id like to run a couple of ideas past you (as my budget is a little bit limited ):

1. would it be possible to fit some motorised three point valve which is normally open, so if the cylinder stat reaches 65C it operates the valve which diverts the stove hot water away from the cylinder to say a dump radiator. Also if the power fails the valve would fail in the same safe position (to the dump radiator)?

2. in the interest of cost and complexity - have a vented cylinder but have a pump on the hot water circuit (showers and hand basins) to account for the fact that the most outlets would be above the cold water tank?

thanks again

your advise is very much appreciated!

shane0007

Simonomis wrote: »

Hi Shane007,

Thank you - thats what I was worried about! I think the Firebird heat exchanger is number one choice but if you dont mind id like to run a couple of ideas past you (as my budget is a little bit limited ):

1. would it be possible to fit some motorised three point valve which is normally open, so if the cylinder stat reaches 65C it operates the valve which diverts the stove hot water away from the cylinder to say a dump radiator. Also if the power fails the valve would fail in the same safe position (to the dump radiator)?

2. in the interest of cost and complexity - have a vented cylinder but have a pump on the hot water circuit (showers and hand basins) to account for the fact that the most outlets would be above the cold water tank?

thanks again

your advise is very much appreciated!

Sorry no. You cannot have any motorised valves on the solid fuel route to the cylinder or to the rads. You can only have them on the controllable heat source side, i.e. the oil side.
The MV's will fail to the closed position.

I am sorry to say this but budget cannot come into it above safety. It is either done correctly or you cannot do it. I am sure you can find somebody to fit it in any manner you wish, as you have already found out, but it is your home & your ongoing dissatisfaction you will have with the system for years.
It's like buying bald tyres for your car instead of new Bridgestones. Will they work & get you from A to B? Yes, but will they be reliable when you need them most, such as in the ice?
Then, you will wish you got the money together & bought the correct tyres for the car, instead of putting everyone at risk. The lad selling you the tyres also said they would be grand.

Do it right from the start & you won't be wasting money doing it twice.

freddyuk

Consider direct fed cylinder from WBS with twin coils for solar and Oil boiler with Heat exchanger for DHW? This keeps the cylinder protected from well water corrosion. Ideally you need to try and get the cylinder above the WBS for gravity feed. I have the same problem and have a buffer in attic and DHW cylinder below so can get solar, WBS, Oil boiler all feeding the system. Header tank for buffer needs to be just high enough over buffer. All open vent.
I would have fitted sealed dhw if i had option at the time. I pump the showers no problem at all. I also fitted pump for sinks/basins.
You can get double or triple coil cylinder with Heat Exchanger all plumbed in.

Simonomis

shane0007 wrote: »

Sorry no. You cannot have any motorised valves on the solid fuel route to the cylinder or to the rads. You can only have them on the controllable heat source side, i.e. the oil side.
The MV's will fail to the closed position.

I am sorry to say this but budget cannot come into it above safety. It is either done correctly or you cannot do it. I am sure you can find somebody to fit it in any manner you wish, as you have already found out, but it is your home & your ongoing dissatisfaction you will have with the system for years.
It's like buying bald tyres for your car instead of new Bridgestones. Will they work & get you from A to B? Yes, but will they be reliable when you need them most, such as in the ice?
Then, you will wish you got the money together & bought the correct tyres for the car, instead of putting everyone at risk. The lad selling you the tyres also said they would be grand.

Do it right from the start & you won't be wasting money doing it twice.

Shane - totally agree - I would not like to be worrying about the safety of my family because of cut corners - tis why im asking you guys

Simonomis

freddyuk wrote: »

Consider direct fed cylinder from WBS with twin coils for solar and Oil boiler with Heat exchanger for DHW? This keeps the cylinder protected from well water corrosion. Ideally you need to try and get the cylinder above the WBS for gravity feed. I have the same problem and have a buffer in attic and DHW cylinder below so can get solar, WBS, Oil boiler all feeding the system. Header tank for buffer needs to be just high enough over buffer. All open vent.
I would have fitted sealed dhw if i had option at the time. I pump the showers no problem at all. I also fitted pump for sinks/basins.
You can get double or triple coil cylinder with Heat Exchanger all plumbed in.

Hi freddyuk - am i right in saying the system you are describing is a thermal store? ive seen this called a "Copper Stratification Thermal Store" it has a tank incorporated?

freddyuk

It is a thermal store in a buffer tank sort of way. I cannot get a huge cylinder in the attic so 250 is it. By siting it over the WBS I get good gravity feed. Also very close to the solar thermal input. It has two coils. No internal tank. Solar goes in the lower coil. I then connected the lower standard (twin coil) DHW cylinder indirectly via the second buffer coil via a temperature differential switch. It constantly feeds hot water down to the DHW cylinder if the buffer is 2c higher than the DHW.The WBS is connected directly to the buffer. I then changed the pumped feed circuit to the DHW to be direct to increase efficiency. I have no issue with de stratification as the buffer is pretty equal and I do not draw hot water directly off it. If I used the second coil indirect it would have no effect at all.
If you really cannot get a decent sized store in the attic you can connect two smaller cylinders together to increase capacity.

Simonomis

freddyuk wrote: »

It is a thermal store in a buffer tank sort of way. I cannot get a huge cylinder in the attic so 250 is it. By siting it over the WBS I get good gravity feed. Also very close to the solar thermal input. It has two coils. No internal tank. Solar goes in the lower coil. I then connected the lower standard (twin coil) DHW cylinder indirectly via the second buffer coil via a temperature differential switch. It constantly feeds hot water down to the DHW cylinder if the buffer is 2c higher than the DHW.The WBS is connected directly to the buffer. I then changed the pumped feed circuit to the DHW to be direct to increase efficiency. I have no issue with de stratification as the buffer is pretty equal and I do not draw hot water directly off it. If I used the second coil indirect it would have no effect at all.
If you really cannot get a decent sized store in the attic you can connect two smaller cylinders together to increase capacity.

Hi Freddy,

I think I understand your set up - the problem I have is that we have extended into the loft area so the area above the collars in the roof is only about 300mm high there is space for a cylinder sitting on a step at the side of the chimney and boxed in by stud wall either side (ill get a picture today to show all) but as you walk around the upstairs area the water level in this tank would be about chest height - there is no higher position in the house. Unfortunately there is no room upstairs for a cylinder so it has to go downstairs.

I hope I am allowed to post a link to a website? im not pushing this particular brand its just that it shows a setup that might work:

http://www.joulesolutions.ie/Copper_Stratification_Thermal_Store/294

Latro

http://www.boards.ie/vbulletin/showthread.php?t=2057133656

post no3

freddyuk

Will your return to the stove be higher than the stove ? You may have trouble getting a decent gravity flow.
Are you installing solar thermal or not?
How are you heating upstairs?
What size cylinder can you fit in. How much space to the ridge ie. is it 300mm into ridge?
Where is your cistern? (you have a well pump to where?)
It all needs to be considered carefully as you need a header tank somewhere.
Pumps make a noise especially in a small property so I would consider this very carefully.

Simonomis

freddyuk wrote: »

Will your return to the stove be higher than the stove ? You may have trouble getting a decent gravity flow.
Are you installing solar thermal or not?
How are you heating upstairs?
What size cylinder can you fit in. How much space to the ridge ie. is it 300mm into ridge?
Where is your cistern? (you have a well pump to where?)
It all needs to be considered carefully as you need a header tank somewhere.
Pumps make a noise especially in a small property so I would consider this very carefully.

Hi Freddy,

Will your return to the stove be higher than the stove ? You may have trouble getting a decent gravity flow.
I think the return will be about the same height - the flow would be a bit higher

Are you installing solar thermal or not?
I would like the option so I will get a triple coil cylinder but install solar at a later date

How are you heating upstairs?
Radiators from all heating sources

What size cylinder can you fit inI think we would need 250L.

How much space to the ridge ie. is it 300mm into ridge?Yes 300mm to ridge

Where is your cistern? (you have a well pump to where?)If thermal store then integrated with cylinder - the well pump is in an outhouse at ground level with an expansion vessel currently reading 2bar

It all needs to be considered carefully as you need a header tank somewhere.
there is enough space for a tank for the stove

Pumps make a noise especially in a small property so I would consider this very carefully.yeah its something I havent considered

freddyuk

If you are thinking of having solar then you need to plan where this will go as there is a pump station etc to go somewhere. More noise! Can you site this outside on the ground.
You have a very small cylinder for running rads so I suggest you do a proper calculation of your heat requirement and go from there. A big stove in a small room is going to be a bad idea.
You should not be pumping house supply from a well supply you should be pumping from a cistern that the well pump fills up except for maybe kitchen tap. Also it needs filtering.
All this needs some researching to get it right.

Simonomis

Freddy thanks, that great advise - I will definitely look into pumping from a water cistern - makes perfect sense. I intend on buying a bigger stove when finances allow but for now the one that's there will do 7 rads and there are 7 rads in the house (only a small two bed cottage)