A few UVC/TS and thermostat questions?

[JamieM]

In the next couple of weeks, we are going to be talking to plumbers about getting a quote for our 1^st fix plumbing.

At the minute the architect has specified a UVC (300L in size I think) and a GSHP.  We are no longer getting a GSHP due to cost and the government incentives removed here in NI.

 

And we are now thinking of a system oil boiler.  I am aware that oil prices will continue to rise.  (Would also consider an ASHP monobloc if we could find a local plumber willing to install/configure it and if the install cost was similar to the oil boiler (I’m not sure that is likely)).

 

I do have a few questions below which I am going to ask the plumber but thought I’d ask on here first just encase the plumber I talk to isn’t familiar to more insulated/sealed houses.

 

1)      UVC/TS? - Any thoughts on which would be better for us? I had thought a TS and maybe a larger one (say 500L) be good for storing heat for a couple of days generated from PV?

 

2)      Where to put the UVC/TS? Hotpress/airing cupboard(which is upstairs) or the utility or garage downstairs?  (if its upstairs and the size is greater than 300L I may have to check the joists can carry the weight)

 

3)      Thermostats in every room? We had thought of just going for one downstairs and one upstairs though our spark had never heard of this and he said he has always provided the electric cabling for one in every room? The reason we had thought of just one for downstairs was because I was once told that having thermostats in every room can cause and oil boiler to be starting and stopping a lot and short cycling which isn’t the best way to run an oil boiler efficiently?

 

4)      Is it worth making one shower electric encase anything happens to the boiler?

 

Bit of background on the build

 

1 bathroom downstairs with a shower

2 bathrooms upstairs - 1 with a shower and 1 with a bath and shower

Overall house size is 2600sqft

Currently just the 2 of us but do plan a family in future – 2 or 3 kids.

We are planning on getting PV though won’t be till the end of the build – want to make sure we don’t run out of money.

Insulation - Floor/roof/walls around 0.13-0.15 and the windows averaging around 0.8Uw (Ug =0.5 and Uf = 1/1.1)

Heating outputs - Underfloor downstairs and radiators on the 1^st floor. (no idea if we’ll need the radiators or not but the missus is insisting)

Air tightness – trying to keep it reasonably air tight but it is a block built house.

We are also having a Wood burning stove though it isn’t going to be connected to the heating system.

We have no option of piped gas now or anytime in the future. This would have been my preferred option.

Keep meaning the check the water pressure we have but haven’t got round to that yet.

thanks

 

Jamie

Edited September 26, 2016 by JamieM
Added in house size

[Temp]

46 minutes ago, JamieM said:

The reason we had thought of just one for downstairs was because I was once told that having thermostats in every room can cause and oil boiler to be starting and stopping a lot and short cycling which isn’t the best way to run an oil boiler efficiently?

 

A correctly set up TS will stop short cycling.

 

When a room stat calls for heat the system draws that heat from the TS without firing up the boiler. After some time this cools the TS and the stat on the TS fires up the boiler topping it up with heat again. The two sides operate independently. The room stats can come on and off many times before the TS cools far enough to trigger the boiler. Once triggered the boiler runs in one long burn until the store is hot again.  This way the TS stops the boiler doing a lot of short burns.

 

This is more important for an oil boiler than a gas boiler. Gas boilers can turn down ("modulate") the size of the flame to reduce the output power. The vast majority of oil boilers can't do that, they can only turn the flame on and off (cycle).

 

We're glad we opted for individual room stats as it allows us to switch off/down spare rooms and have better control over the temperature (some rooms have more or less solar gain than others). Some rooms we have warmer at different times of the day etc. We even put separate stats in the bathrooms (Heatmiser with remote sensor). Great having the floor warm first thing.

 

Remember that for each stat you need an additional zone (separate floor loop and actuator on the manifold). This might add to the cost but it depends on the size of the house. If you are building a big house then you may need lots of floor loops anyway. Normally each loop is limited to 100m of pipe including the run to the manifold. Really big rooms sometimes have two floor loops controlled by one room stat.

 

 

  

 

 

 

 

[Temp]

The plumber might tell you that rads and UFH need different temperature water (rads hotter than UFH). That would be the case in a badly insulated house needing high output but with luck your rads will be sufficient operating at the lower temperature of the UFH.  If in doubt perhaps make the rads bigger than they would normally be so they work fine at the UFH flow temperature.

 

The plumber might suggest running the rads off the boiler rather than the TS. I don't think I would do that but perhaps have him do the layout so you could switch the rads from the TS to the boiler if things really didn't work out and you needed to boost the output from them.

 

[Declan52]

I have more or less the same set up with a 350l TS feeding the ufh downstairs and rads on the first floor. I use a pellet stove for my heat needs as well as PV for prob 5/6 months of the year. 

We also questioned if we would need an electric shower as a backup but in truth the water is usually hot enough during the summer with excess PV and the stove would be on maybe every 2nd day during the winter so the TS is rarely cold. 

I heat the water in the TS to 65 degrees and have a manifold system to feed the rads and then the same for the ufh where it gets mixed with cold water to go into the system at 32.

Put the rads in as if it isn't as warm upstairs as you hope your life won't be worth living!!!

Can you not connect up the stove up to the heating system to use as backup option. Extra cost wouldn't be that much.

[JamieM]

47 minutes ago, Declan52 said:

I have more or less the same set up with a 350l TS feeding the ufh downstairs and rads on the first floor. I use a pellet stove for my heat needs as well as PV for prob 5/6 months of the year. 

We also questioned if we would need an electric shower as a backup but in truth the water is usually hot enough during the summer with excess PV and the stove would be on maybe every 2nd day during the winter so the TS is rarely cold. 

I heat the water in the TS to 65 degrees and have a manifold system to feed the rads and then the same for the ufh where it gets mixed with cold water to go into the system at 32.

Put the rads in as if it isn't as warm upstairs as you hope your life won't be worth living!!!

Can you not connect up the stove up to the heating system to use as backup option. Extra cost wouldn't be that much.

We could connect the stove up. It's more me being lazy and not wanting to always be adding more fuel to it if it did have a back boiler. Plus we were only planning a small 5kw stove. 

[Declan52]

If you are putting in  a stove then it's going to need fuel so you might as well heat the water when it's lit.

[JamieM]

But do they not use up a lot more wood/coal when heating up a back boiler? 

[JamieM]

On 26/09/2016 at 17:42, Declan52 said:

I have more or less the same set up with a 350l TS feeding the ufh downstairs and rads on the first floor. I use a pellet stove for my heat needs as well as PV for prob 5/6 months of the year. 

We also questioned if we would need an electric shower as a backup but in truth the water is usually hot enough during the summer with excess PV and the stove would be on maybe every 2nd day during the winter so the TS is rarely cold. 

I heat the water in the TS to 65 degrees and have a manifold system to feed the rads and then the same for the ufh where it gets mixed with cold water to go into the system at 32.

Put the rads in as if it isn't as warm upstairs as you hope your life won't be worth living!!!

Can you not connect up the stove up to the heating system to use as backup option. Extra cost wouldn't be that much.

 

@Declan52, did you put your TS on the ground floor or upstairs?

 

@Temp same question to you and what size did you go for?

 

thanks

 

Jamie

Edited September 28, 2016 by JamieM

[Declan52]

Mine is on the first floor joists but it's sitting on top of an internal block wall. 

[Nickfromwales]

On 26 September 2016 at 21:50, JamieM said:

But do they not use up a lot more wood/coal when heating up a back boiler? 

Yup . 

Question is of cost of wood, convenience / inconvenience and how much heat your home will withstand, and for how long. 

Some folk are happy to tend to a boiler, I'm not one of them. 

On 26 September 2016 at 16:07, JamieM said:

I may have to check the joists can carry the weight)

Do you have block or TF ground floor walls?

[JamieM]

9 minutes ago, Nickfromwales said:

Yup . 

Question is of cost of wood, convenience / inconvenience and how much heat your home will withstand, and for how long. 

Some folk are happy to tend to a boiler, I'm not one of them. 

Do you have block or TF ground floor walls?

 

I'm also quite lazy when it comes to filling up the stove.

 

All ground floor walls are block, some of the wall upstairs are also.  The door into the hotpress/airing cupboard (upstairs) is block either side so cant easily be made bigger. At the start didnt think of potentially having a larger TS.

 

Also directly above a block wall. (didnt even realise unitl I checked there)

Edited September 28, 2016 by JamieM

[Nickfromwales]

No problem with weight then, as you can just straddle the two downstairs walls to take the extra weight of a larger TS. If your going with oil then I'd 100% recommend a TS so you can pulse heat to it, as it won't modulate ( as Temp has already stated ). That'll get the best efficiency and stop short cycling so imho is essential not preferential

I wouldnt go less than 400ltr tbh, so the design weight needs to be taken as circa 500kg, but if Pv is deffo in the design then I'd say go a little larger at 500ltr ( 600 kg ). 

Fit it in the airing press hot cupboard and use the latent heat loss to your advantage, remembering of course that this will be hot all year round as it'll be providing dhw. 

Storing heat for "a c

On 26 September 2016 at 16:07, JamieM said:

be good for storing heat for a couple of days generated from PV?

Pv will generate daily, so storing for a couple of days is not a consideration you should be worrying about. If a TS is providing space heating ( as a buffer for the oil ) and DHW, it'll need daily recharge howsoever that's provided. 

[Temp]

Quote

@Temp same question to you and what size did you go for?

 

I went with a 300L store. If building again I would go for bigger but we had issues fitting it through doorways. Specify extra insulation if you can.

 

 

[JamieM]

20 minutes ago, Nickfromwales said:

No problem with weight then, as you can just straddle the two downstairs walls to take the extra weight of a larger TS. If your going with oil then I'd 100% recommend a TS so you can pulse heat to it, as it won't modulate ( as Temp has already stated ). That'll get the best efficiency and stop short cycling so imho is essential not preferential

I wouldnt go less than 400ltr tbh, so the design weight needs to be taken as circa 500kg, but if Pv is deffo in the design then I'd say go a little larger at 500ltr ( 600 kg ). 

Fit it in the airing press hot cupboard and use the latent heat loss to your advantage, remembering of course that this will be hot all year round as it'll be providing dhw. 

Storing heat for "a c

Pv will generate daily, so storing for a couple of days is not a consideration you should be worrying about. If a TS is providing space heating ( as a buffer for the oil ) and DHW, it'll need daily recharge howsoever that's provided. 

 

cheers for this.

 

i meant the block walls getting into the airing press hot cupboard were already built upstairs so the door into it is around 910mm wide. As @Temp has said above, this may be an issue with fitting a 400 - 500 TS.  (thinking a telford by the way and was going to take a reccommendation as to the insulation to add to it)

[Nickfromwales]

I need to create a new thread regarding the extra insulation etc as I've discussed this at great length with Roger at Telford and have been assured the standard ( hi performance ) insulation which is installed beneath the cosmetic metal 'jacket' would perform better than the extra depth spray foam. The confusion was around @Shell820810 's issue when hers turned up with no extra spray insulation, but the metal jacket, which shouldn't have been on it. 

It boiled down to the thicker spray insulation being cheaper than the high performance insulation and the metal jacket combined, so in essence you'd get a bulkier, cheaper to buy cylinder which had a loss of around .5kw per 24hrs. The exact figures escape me now but you deffo want to order the regular cylinder with the HP insulation and metal jacket. 

Regarding costs / savings I was assured by Trevor at Cylinders2go that there would not be any premium, regardless, when buying through him ( mentioning the forum and my username ).  

 

This is is for a 400, but I think the dia stays the same for a 500 but the height changes to 1810mm iirc. The naked tank is, I believe, designed to fit through a standard 760mm doorway . 

Just remember that the immersion / s need to face front so you can change them if necessary without removing the cylinder.  

[Declan52]

Put a plumb piece of timber on the block walls at the doorway to allow you to plaster the walls. This will mean that you can leave the door frame out which will give you another few inches which hopefully will be enough to get a larger ts in place. Easy enough then to fit the frame to suit the plaster which should be plumb if the timber was set correct and hang the door. Just use the likes of concrete screws so in the future if it needs to come out it's not a messy job.

[Shell820810]

We have 33" doors and had no bother getting the 500l Telford ts through. @Nickfromwales my sister is looking the same setup as what we have. Should she ask for what we asked for or what we got?

[Nickfromwales]

2 hours ago, Shell820810 said:

We have 33" doors and had no bother getting the 500l Telford ts through. @Nickfromwales my sister is looking the same setup as what we have. Should she ask for what we asked for or what we got?

What you got, 100%. Lower standing losses and physically smaller for the same capacity. 

Apologies for the seemingly bum steer but after you pinged me on EB I got onto the phone ( as you're aware ) and got to the bottom of what's better / cheaper etc and the spray foam is a slightly budget version of the product as your buying cheaper foam and they're not fitting the white powder coated case if they go that route. 

As above, the final confusion was Roger telling me it should cost more for the jacket, but then Trevor saying he wouldn't charge extra either way. 

With those cards on the table it's a no-brainer. Metal jacket, HP insulation and more compact product all the way. 

[Shell820810]

17 minutes ago, Nickfromwales said:

What you got, 100%. Lower standing losses and physically smaller for the same capacity. 

Apologies for the seemingly bum steer but after you pinged me on EB I got onto the phone ( as you're aware ) and got to the bottom of what's better / cheaper etc and the spray foam is a slightly budget version of the product as your buying cheaper foam and they're not fitting the white powder coated case if they go that route. 

As above, the final confusion was Roger telling me it should cost more for the jacket, but then Trevor saying he wouldn't charge extra either way. 

With those cards on the table it's a no-brainer. Metal jacket, HP insulation and more compact product all the way. 

Great, so its the same price. Is a standard insulation spec then, we don't need to state depth etc?

[Nickfromwales]

Nope. . 

[Shell820810]

On 26/09/2016 at 17:21, Temp said:

 

A correctly set up TS will stop short cycling.

 

When a room stat calls for heat the system draws that heat from the TS without firing up the boiler. After some time this cools the TS and the stat on the TS fires up the boiler topping it up with heat again. The two sides operate independently. The room stats can come on and off many times before the TS cools far enough to trigger the boiler. Once triggered the boiler runs in one long burn until the store is hot again.  This way the TS stops the boiler doing a lot of short burns.

 

This is more important for an oil boiler than a gas boiler. Gas boilers can turn down ("modulate") the size of the flame to reduce the output power. The vast majority of oil boilers can't do that, they can only turn the flame on and off (cycle).

 

 

 

 

 

 

  

 

 

 

 

What's the best way of going about this- its the stats and electrics that control it?

So we would want to heat the tank to say 90c and then once the temp dropped to say 70c it would call for the boiler then? I think we have two stats on the TS, high and lower down.