Heating Design

[vfrdave]

I have been avoiding this post for a while and also been busy doing other things at the house.  I need to sort out my heating design and it is proving difficult with varying opinions here in the land of the hotpress.  I have a plumber who I am relatively happy with and comes highly recommended we just need to bottom out the design somewhat.

Above is the floor plan and I have posted on this previously a long time ago, never thought it would take us this long to get to the point we are at.

 

We are going to have UFH throughout along with towel rads in bathroom/en-suites, feature radiator in reception (I don't anticipate this putting much heat out) and provision for radiators in the garage.  This will all be fed from an oil boiler (gas is not an option, ASHP I have ruled out and PV wont be happening).  I understand that oil and UFH are not conducive for optimum performance but measures can be taken to alleviate this.  The default position with almost all plumbers and heating designers here is to just feed the UFH via blending valve straight from the boiler, I hear @Nickfromwales scream what about short cycling on a boiler that cant modulate like a gas one  (I have read plenty on here already).  Some just don't get it is all I will say.  Others agree to disagree.

 

My options are as I see it:-

 

• Oil boiler with buffer and UVC.  Question here is what size of buffer?  It was suggested to me 500L but that was then going to also feed a UVC which I couldn't quite get my head around.
• Other option as I understand would be a 400/500L thermal store to do the lot.  Any time I raise this in discussions no-one understands why I might do this if I have no wood burner etc dumping heat into it.

 

Are there any other options?

I dont really understand it all myself and my head has gone to mush with all the reading I have done.  I fear my plumber may run for the hills if I dictate too much of the design to him.

 

Please help!

 

[Alexphd1]

Nice project.

 

Oil boilers are 100% heat output or nothing. For this I would I wouldn't be running UFH direct but I have seen it done this way a lot. My choice would be a thermal store (dhw coil not plate heat exchanger) with dhw pump return (design of house). You cam br smart when you control the pump ie when somebody switches on bathroom light pump comes on. 

 

Heads up I picked up a new stainless steel 500l thermal store with two coils for £900 Inc vat del of eBay a few weeks ago. He has stiĺl 1 left. Also if going pumped DHW bronze pumps (grundfos) are a lot cheaper off eBay compared to plumb merchants. 

Edited April 3, 2018 by Alexphd1

[vfrdave]

16 minutes ago, Alexphd1 said:

with dhw pump return (design of house)

I assume you say this because of potential long runs? I'm not limited to having tank/store in plant room, was thinking more store 1

[Alexphd1]

Store 1 makes more sense for tank! My mistake. Makes nice warm press with heat loss aswell.

[Nickfromwales]

If your plumber will work to a design then great. If they won't, and are adamant about firing ~26kw or more heat directly into a manifold that can only consume about a quarter of that ( IF the house was being heated from cold, because after it's up to temp it's probably less again ) then you have to make a choice. It's your house and your paying the bill for the oil, plus your going to pay extra maintenance if the boiler can't fire for reasonably long burns eg run 'clean' and needs heavier cleaning of the baffles more frequently. 

You don't need to justify having a TS, and you certainly don't need a solid fuel burner to justify it being fitted either. 

Stick to your guns and ask your plumber for a meeting. Sit him down and explain why you've decided to fit one. If he runs for the hills then he's not much of a professional. ( When asked to fit 600x600 black and white porcelain tiles in a bedroom I didn't say "no way, they're not to my liking" because it wasn't my house. . Instead I fitted them to the best of my ability and the customer was over the moon with them. That's why we get called "professionals" isn't it ?

A lot of plumbers still think an oil boiler can modulate just because it condenses

You will need a hot return if your plumber will do the usual knee-jerk '28mm-22mm-15mm' series plumbing, or you'll have washed your hands in cold water and dried them before getting hot water out of the furthest away basins, especially the cloak. 

 

A TS will best suit your DHW needs IMO, as long as you set it up PROPERLY eg correctly specified controls, again not something to expect from joe public plumber.

If you have a very good cold mains you'll be able to have pretty much constant, instant DHW at very high flow rates, with the ability to run at least 2 good showers at the same time. 

Not having PV is a bad idea IMO, and I'd at least run cables for it now, which is cheap as chips, if it's down to lack of immediate budget rather than purely deciding against. 

[Nickfromwales]

2 hours ago, Alexphd1 said:

Store 1 makes more sense for tank! My mistake. Makes nice warm press with heat loss aswell.

Yup. 

A better central location for the airing cupboard ( aka hot-press ) so even though the TS will have to stay topped up during the day, it can be better utilised to reduce losses, but also utilise the waste heat to keep your undercrackers toasty . 

[vfrdave]

I will pick this up later again, heading out with the girls.

[vfrdave]

On 4/3/2018 at 13:16, Nickfromwales said:

You will need a hot return if your plumber will do the usual knee-jerk '28mm-22mm-15mm' series plumbing

Elaborate on this for my simple  mind specifically the 28mm-22mm-15mm

 

On 4/3/2018 at 13:16, Nickfromwales said:

A TS will best suit your DHW needs IMO, as long as you set it up PROPERLY eg correctly specified controls

This is the bit that concerns me more, convincing him to put a TS may not be so bad but the controls is the difficulty.  I dont want to end up with the conundrum that @newhome has with her TS and controls.

 

On 4/3/2018 at 13:16, Nickfromwales said:

Not having PV is a bad idea IMO

Not having any RHI in Northern Ireland makes this more or less a non-starter for me, plus I like my slate roof too much to now cover it with PV panels.

[Nickfromwales]

1 minute ago, vfrdave said:

Elaborate on this for my simple  mind specifically the 28mm-22mm-15mm

For high flow rates, the norm is to start off from the hot water cylinder in 28mm pipework to where perhaps the first bathroom gets teed off, then it reduces to 22mm as it gets further in, and then reduces finally to serve each outlet at the end of the run. 

3 minutes ago, vfrdave said:

This is the bit that concerns me more, convincing him to put a TS may not be so bad but the controls is the difficulty.  I dont want to end up with the conundrum that @newhome has with her TS and controls.

It's not rocket science, and if he can do an S-plan or Y-plan he can do this. If they can't wire S / Y then bid them fairwell. 

5 minutes ago, vfrdave said:

Not having any RHI in Northern Ireland makes this more or less a non-starter for me

It's nothing to do with RHI if you buy the kit cheap and DIY, foregoing the MCS price tag. 

7 minutes ago, vfrdave said:

plus I like my slate roof too much to now cover it with PV panels.

You'll soon stop staring at your roof and be more focussed on your energy bill, which will only keep going up and up and up. 

[vfrdave]

7 minutes ago, Nickfromwales said:

It's not rocket science, and if he can do an S-plan or Y-plan he can do this. If they can't wire S / Y then bid them fairwell

I even understand the above having put wireless stats in my previous house.

 

Think I need to have a stab at drawing out my design to fully understand it.

[Nickfromwales]

7 minutes ago, vfrdave said:

I even understand the above having put wireless stats in my previous house.

 

Think I need to have a stab at drawing out my design to fully understand it.

Crack on. May as well start at the start . 

[vfrdave]

12 hours ago, Nickfromwales said:

For high flow rates, the norm is to start off from the hot water cylinder in 28mm pipework to where perhaps the first bathroom gets teed off, then it reduces to 22mm as it gets further in, and then reduces finally to serve each outlet at the end of the run. 

The hot return scenario, if using manifolds for hot water distribution does this help with this scenario?

[Nickfromwales]

3 hours ago, vfrdave said:

The hot return scenario, if using manifolds for hot water distribution does this help with this scenario?

Not entirely. 

 

On this one there will still be a hot return pump ( yet to be fitted in the pipe directly above that pump ) which only returns from the furthest hot outlet, the kitchen sink. 

 

For this installation I set it up so that the hot to the kitchen sink is the furthest manifold outlet away from the manifold supply inlet, so the hot return travels through all the large bore hot pipework from the water heater ( Sunamp ) and all the way through the hot manifold, and in doing so it pre-heats the whole manifold, thus killing off the dead leg that would otherwise exist.

Manifolds, unless directly off the hot water device, still cause an issue because they need large bore runs tobthwm before they reduce accordingly, but they do reduce losses vs traditional series plumbed installations, so each case has to be designed specifically and will be unique. 

[Alexphd1]

@Nickfromwales very tidy install! Where did you get the hot/cold manifold from?

[Nickfromwales]

14 hours ago, Alexphd1 said:

@Nickfromwales very tidy install! Where did you get the hot/cold manifold from?

Enjoy.

 

[dpmiller]

don't think I could enjoy them at that price...

[Nickfromwales]

5 hours ago, dpmiller said:

don't think I could enjoy them at that price...

You get what you pay for  

[Alexphd1]

@Nickfromwales Tidy with the hep fittings but v expensive. Have a look at antares international a European based supplier very strict trade only though. Have not bought anything from them for ages and got a catalogue through door a few weeks ago.

[Nickfromwales]

57 minutes ago, Alexphd1 said:

@Nickfromwales Tidy with the hep fittings but v expensive. Have a look at antares international a European based supplier very strict trade only though. Have not bought anything from them for ages and got a catalogue through door a few weeks ago.

Some other manifolds I've seen have been smaller bore and noisy when flowing. Be interesting to see how they perform. 

My difficulty is experimenting in customers houses, or fitting what I know works reliably. 

[Alexphd1]

Look v similar.

[Nickfromwales]

1 hour ago, Alexphd1 said:

Look v similar.

Looks like your the BH test pilot for those then  

[Alexphd1]

I stepped into that one.....