System boiler and tank or combi and cold booster?
Discussion
Hello all...
We're doing some renovations, we will be changing the boiler and its location as part of it, moving it from the garage to the loft (we're converting the loft).
We have a combi at the moment but with the kids getting a bit older (more and longer showers apparently!) plus putting a second shower room into the loft, we will suffer from lack of flow/pressure when there is high demand for hot water.
The loft space we have is not huge but we can probably get a system boiler on the wall in the eaves and a 200-250l tank in there. The other option is a standard combi but with a boosted cold supply (again 200-250l) which would be in the garage supplying the boiler in the loft.
We will have...
- loft shower room (likely mixer)
- main bathroom with bath and electric shower over (could change to mixer)
- radiators over 3 floors, no underfloor heating.
- no real solar plans as loft conversion may scupper that.
Does anyone have any opinions on the best option to go for? I presume either would fit our needs but I have no experience of either option, particularly how well the boosted cold tank would work.
Thanks
We're doing some renovations, we will be changing the boiler and its location as part of it, moving it from the garage to the loft (we're converting the loft).
We have a combi at the moment but with the kids getting a bit older (more and longer showers apparently!) plus putting a second shower room into the loft, we will suffer from lack of flow/pressure when there is high demand for hot water.
The loft space we have is not huge but we can probably get a system boiler on the wall in the eaves and a 200-250l tank in there. The other option is a standard combi but with a boosted cold supply (again 200-250l) which would be in the garage supplying the boiler in the loft.
We will have...
- loft shower room (likely mixer)
- main bathroom with bath and electric shower over (could change to mixer)
- radiators over 3 floors, no underfloor heating.
- no real solar plans as loft conversion may scupper that.
Does anyone have any opinions on the best option to go for? I presume either would fit our needs but I have no experience of either option, particularly how well the boosted cold tank would work.
Thanks
System boiler and unvented cylinder will be far superior, slightly less to go wrong in the boiler, better flow rate and should your boiler go wrong your have an immersion heater back up for hot water.
Look at the vaillant ecotec plus 6 series nice bits of kit.
Draw backs of boiler in the loft are your best climbing up there to reset it or change any boiler settings.
Obviously will come at a cost over the combi
Ss
Look at the vaillant ecotec plus 6 series nice bits of kit.
Draw backs of boiler in the loft are your best climbing up there to reset it or change any boiler settings.
Obviously will come at a cost over the combi
Ss
We have a system boiler (14yo viessman vitodens 100) and unvented hot cylinder (7yo OSO deltacoil) and are very happy with it. All be it yet to have teenagers!
The system boiler is literally identical to the combi, only without the plate heat exchanger. Four pipes out, same diverter valve and primary heat exchanger.
The system boiler is literally identical to the combi, only without the plate heat exchanger. Four pipes out, same diverter valve and primary heat exchanger.
Ensure you have the joists for the cylinder sufficiently strong as at capacity it will be a quarter of tonne.
We’ve just gone for a horizontal version in the basement onto concrete floor, might help spread the load a little better in a loft?
Also be aware if there is a problem they need to be accessible / come out so don’t box them in too tightly.
Had a system / cylinder set up previously for 20 years and added the output of the solar panels straight into it via the immersion from a 3.8kW array, didn’t need gas from April to October generally for hot water….
We’ve just gone for a horizontal version in the basement onto concrete floor, might help spread the load a little better in a loft?
Also be aware if there is a problem they need to be accessible / come out so don’t box them in too tightly.
Had a system / cylinder set up previously for 20 years and added the output of the solar panels straight into it via the immersion from a 3.8kW array, didn’t need gas from April to October generally for hot water….
I had my solar installed when I did my loft conversion if that helps you.
I would strongly recommend going tank, given direction of travel to lower emission sources (e.g. HP) - it'll mean you can swap that out. Given Gas prices, also worth probably getting a heat pump costed considering the size of the grant at the moment.
I would strongly recommend going tank, given direction of travel to lower emission sources (e.g. HP) - it'll mean you can swap that out. Given Gas prices, also worth probably getting a heat pump costed considering the size of the grant at the moment.
With showers, you might want to consider your supply limitations.
Water companies are tending to reduce the pressure at the main in the road, to reduce leaks.
You may not be guaranteed enough pressure and flow to run two decent showers without a buffer tank and pump.
I know someone who is sticking with old school header tank in the loft and a shower pump for this reason.
You can get through a lot of energy and water with showers.
It's also important that two showers will run without interfering with each other. Not always a given!
Also, I think it would at least be sensible to plan for a heat pump next time around, your boiler might want replacing in 10 years, how hard will it be to install a heat pump?
Water companies are tending to reduce the pressure at the main in the road, to reduce leaks.
You may not be guaranteed enough pressure and flow to run two decent showers without a buffer tank and pump.
I know someone who is sticking with old school header tank in the loft and a shower pump for this reason.
You can get through a lot of energy and water with showers.
It's also important that two showers will run without interfering with each other. Not always a given!
Also, I think it would at least be sensible to plan for a heat pump next time around, your boiler might want replacing in 10 years, how hard will it be to install a heat pump?
OutInTheShed said:
With showers, you might want to consider your supply limitations.
Water companies are tending to reduce the pressure at the main in the road, to reduce leaks.
Yeah, we have had this. Bit of a pain. Water companies are tending to reduce the pressure at the main in the road, to reduce leaks.
After a bit of a fight were back upto good enough for an ok shower (or two) but last summer it was a bit ridiculous. Around 20% below the statutory minimum.
Six years ago just after we got rid of the cold tank we also had 6months supply interruptions while they ironed out the teething issues with their "direct inline' pumps having taken the local water tower out of service.
That said, we still get an ok shower, with the pump noise, and could fit a whole house cold water booster if we ever needed to.
Cold water header tanks work well, but for two showers you need a bloomin large one. Nothing worse than the cold water header running out and the shower suddenly switching to neat 75c hotwater in your noggin. You get good at spotting the pump note change and getting the f
k outta there!Thanks all.
Loft floor will be new timbers of short span in that area so weight bearing should be fine. Option to easily double some up if unsure.
Flow rate is only 15 l/min, so borderline for an unvented tank. An accumulator option probably on the cards. Static/dynamic pressures I don't know yet, getting a pressure gauge on Monday.
Heat pump I'm not convinced on. I like the option but install would be a problem. We have nowhere for the unit to go outside. Solar equally an issue as with loft converted with a full width dormer, we have no south-facing sloping roof, so any panels would need to be mounted on the flat roof of the dormer or the flat roof of the single storey ground floor extension. Not ideal but not impossible.
Loft floor will be new timbers of short span in that area so weight bearing should be fine. Option to easily double some up if unsure.
Flow rate is only 15 l/min, so borderline for an unvented tank. An accumulator option probably on the cards. Static/dynamic pressures I don't know yet, getting a pressure gauge on Monday.
Heat pump I'm not convinced on. I like the option but install would be a problem. We have nowhere for the unit to go outside. Solar equally an issue as with loft converted with a full width dormer, we have no south-facing sloping roof, so any panels would need to be mounted on the flat roof of the dormer or the flat roof of the single storey ground floor extension. Not ideal but not impossible.
OutInTheShed said:
With showers, you might want to consider your supply limitations.
Water companies are tending to reduce the pressure at the main in the road, to reduce leaks.
You may not be guaranteed enough pressure and flow to run two decent showers without a buffer tank and pump.
I know someone who is sticking with old school header tank in the loft and a shower pump for this reason.
You can get through a lot of energy and water with showers.
It's also important that two showers will run without interfering with each other. Not always a given!
One of my reasons for staying with a loft tank and pumped showers - when we moved here 30+ years ago water pressure was excellent but it been reduced a lot in the last 10 years to the point where some neighbours who've gone the combi route are regretting the decision because showers are rubbishWater companies are tending to reduce the pressure at the main in the road, to reduce leaks.
You may not be guaranteed enough pressure and flow to run two decent showers without a buffer tank and pump.
I know someone who is sticking with old school header tank in the loft and a shower pump for this reason.
You can get through a lot of energy and water with showers.
It's also important that two showers will run without interfering with each other. Not always a given!
Personally, I'd want to be insulating myself against any future changes (for the worse) on either the incoming flow rate or the water pressure.
So, I'd be going for stored water (hot and cold) which was then pumped. If you've got the room, I'd have an individual pump for each bathroom. The kitchen and downstairs loo can cope without a pump, although depending on your choice of kitchen tap, you might need a hot water only booster pump for that.
So, I'd be going for stored water (hot and cold) which was then pumped. If you've got the room, I'd have an individual pump for each bathroom. The kitchen and downstairs loo can cope without a pump, although depending on your choice of kitchen tap, you might need a hot water only booster pump for that.
Just co-incidence, I guess, but since we switched to a pressurised system four years ago we ve had many occasions of very low pressure or no supply at all.
It’s really quite a shock when it first happens as you’ve got absolutely no usable water at all in the house. At least with the cold water tank we could get water for toilet flushing etc out of the hot tap. In my parents house every tap worked off the tank apart from the cold in the kitchen.
It’s really quite a shock when it first happens as you’ve got absolutely no usable water at all in the house. At least with the cold water tank we could get water for toilet flushing etc out of the hot tap. In my parents house every tap worked off the tank apart from the cold in the kitchen.
Edited by Sheepshanks on Monday 28th September 14:22
r44flyer said:
Thanks all.
Loft floor will be new timbers of short span in that area so weight bearing should be fine. Option to easily double some up if unsure.
Flow rate is only 15 l/min, so borderline for an unvented tank. An accumulator option probably on the cards. Static/dynamic pressures I don't know yet, getting a pressure gauge on Monday.
Heat pump I'm not convinced on. I like the option but install would be a problem. We have nowhere for the unit to go outside. Solar equally an issue as with loft converted with a full width dormer, we have no south-facing sloping roof, so any panels would need to be mounted on the flat roof of the dormer or the flat roof of the single storey ground floor extension. Not ideal but not impossible.
Solar may be pointless if you don't have a good roof slope to put it on.Loft floor will be new timbers of short span in that area so weight bearing should be fine. Option to easily double some up if unsure.
Flow rate is only 15 l/min, so borderline for an unvented tank. An accumulator option probably on the cards. Static/dynamic pressures I don't know yet, getting a pressure gauge on Monday.
Heat pump I'm not convinced on. I like the option but install would be a problem. We have nowhere for the unit to go outside. Solar equally an issue as with loft converted with a full width dormer, we have no south-facing sloping roof, so any panels would need to be mounted on the flat roof of the dormer or the flat roof of the single storey ground floor extension. Not ideal but not impossible.
What is the future fro your house post 2050?
It's a long time away now, but won't be if you're selling in 10 or 15 years.
There are heat pump systems which are all internal, I don't have any great interest, but maybe it's not a great idea to spend lots of money on work which closes down options long term? Of course your house will be one of many so perhaps a solution will turn up in due course?
Very happy with our unvented cylinder system, installed about 6 yrs ago. We did have to upgrade the water supply into the house.
Pumps out hot water for a bath at cold tap pressures. We can easily run 2 showers at same time. You can notice if there are 2 showers running at same time, but it's still a decent pressure.
Pumps out hot water for a bath at cold tap pressures. We can easily run 2 showers at same time. You can notice if there are 2 showers running at same time, but it's still a decent pressure.
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