Advice on new CH system

[mysteryman]

Tony, as I explained above, on a water priority system you do NOT add any extra for DHW. The boiler will not do CH and DHW at the same time, so you size to the greater load, in this case the CH.

 

[Agile]

Thats correct BUT he is not necessarily going to have a water priority system yet.

In any case if it really needs 44 kW ( which I doubt ) an extra 2 kW becomes irrelevant!

Tony

 

[D_Hailsham]

Here are the results of the calculator, I've broken them down;

Main House = 31.47kw
Granny annex = 12.55kw

How big is your house??

I have a 4 bed detached which doesn't even need as much heat as your "granny annex"; or is the annex really the gamekeeper's stone-walled cottage?

If you will post the data you entered into the calculator, I can check if you have made any mistakes.

 

[DeltaT2]

Place your bets now people - 12 pages? Maybe 9....

..............You're not wrong Dan.

This must be some size of house?? I think if the OP can afford a large pile like that, I'm sure he could afford to employ the services of a good H&E consultant. At least he'd have some recourse if it going t.ts up.

Well, with advice like WC & undersized boilers I think he may freeze!!...............

 

[mrbutt]

44 kW is a massive heating load. Is it really 12-18 bedrooms?

Are you paying about £3000-£5000 per annum for gas?

You should never size a boiler for an extension planned for a long time into the future as thats inefficient until the extension is built.

Tony

It's not 12-18 bedrooms but it is a large house.

I hope I dont pay anywhere near that in gas mate! At the moment have a 31KW boiler on natural gas and a broken 29KW boiler on LPG. The 31KW we pay around £1500 a year.

After the advice given before by D_Hailsham, I am no longer going to size the boiler for the extension planned.

If you will post the data you entered into the calculator, I can check if you have made any mistakes.

Thanks mate, I will list the information I put in below (was done in 4 seperate parts).

Living Area
Dwelling Type: Detached

Internal Measurements: 2x(10metres), 2x(12metres), 2 floors at 2.4metres high

Outside Walls Type: Filled cavity wall

Window Type: Double Glazed plastic

Roof Type: Pitched with 50-75mm insulation

Extension: 0

DHW: 0

Location: North

Boiler required = 15.47KW



Leisure Rooms
Dwelling Type: Detached

Internal Measurements: 2x(10metres), 1x(9metres), 1 floors at 2.8metres high

Outside Walls Type: Filled cavity wall

Window Type: Double Glazed plastic with 28 Sqm of Glazing

Roof Type: Pitched with 50-75mm insulation

Extension: 0

DHW: 0

Location: North

Boiler required = 9.37KW


Sun Lounge
Dwelling Type: Detached

Internal Measurements: 1x(4metres), 2x(8metres), 1 floor at 2.8metres high

Outside Walls Type: Filled cavity wall

Window Type: Double Glazed plastic with 29 Sqm of glazing

Roof Type: Flat and uninsulated

Extension: 0

DHW: 0

Location: North

Boiler required = 6.03KW


Main House = 30.87KW


Granny Annexe
Dwelling Type: Detached

Internal Measurements: 2x(7metres), 2x(13metres), 2 floors at 2.4metres high

Outside Walls Type: Filled cavity wall

Window Type: Double Glazed plastic

Roof Type: Pitched with 50-75mm insulation

Extension: 0

DHW: 0

Location: North

Granney Annex = 12.55KW

I have filled it in again, slightly different results as I've been rounding off with these figures. The ones I did yesterday were more accurate.


Let me know what you think guys.

 

[D_Hailsham]

Living Area
Dwelling Type: Detached

Boiler required = 15.47KW

I made it 15.74kW. Probably a typo?

This would reduce to 13.55kW with 75mm insulation and even more if you use 250mm insulation

Leisure Rooms
Dwelling Type: Detached? I think you mean semi-d? as there are only three external walls

Boiler required = 9.37KW

Agreed. Better loft insulation would reduce it below 7.39kW

Sun Lounge
Dwelling Type: Detached? 3 walls = semi d
Boiler required = 6.03KW

Agreed.

You say it's a flat uninsulated roof, so presumably nothing can be done about the insulation.

Main House Total= 30.87KW

This will reduce to less than 27kW with better roof insulation

Granny Annexe

12.55kW[/quote]
Agreed. This will reduce to less than 11kW with better insulation.


Summary
Current total requirement = 43.42kW say 44kW
With 250mm loft insulation, the total requirement = 38kW.

 

[mrbutt]

Thanks for taking the time out to work that out mate.

Now I have some questions about fitting insulation. In the granny annex and Leisure rooms the ceilings are the type that run parallel to the roof (ie they are sort of a pitched ceiling), there is no access to lay down some more insulation.
As far as I can see its either pulling the ceiling down (dont want to really as they are already decorated ceilings), or lifting the roof tiles and fitting more insulation. Or is there a better way you know of?

In the Living area, I could easily fit loft insulation as its accessable.

 

[mrbutt]

Also, since we have gathered that I do need approx 40-45KW (as loft insulation can only be applied in some of the places), what is the next step?

As I said before, here are the main 6 boilers I was thinking of;

Atag Q38S
Vaillant EcoTec 46KW Commercial
Vaillant EcoTec Plus 37KW System
Viessmann Vitodens 200W 45KW Commercial
Broag Remeha Avanta Plus 39C (offer conversion to a system boiler)
Broag Remeha Quinta Pro 45

Could people offer comments on the above, with actual experience. Also open to other recommendations if you think there is better for the money.

Do people know the prices of the above boilers? Not RRP but the better deals

 

[D_Hailsham]

Now I have some questions about fitting insulation. In the granny annex and Leisure rooms the ceilings are the type that run parallel to the roof (ie they are sort of a pitched ceiling), there is no access to lay down some more insulation.

So you only have six inches or so between the tiles and the ceilings?

Lifting some tiles is a possibility or it may be possible to blow insulation into the void. Probably best to contact an insulation installer and ask their advice.

As for the boiler, I have reservations about supplying everything from the one boiler. You don't say how far the granny annex is from the main house, but there could be a considerable heat loss in the pipes between the two buildings and control systems will get complicated with programmers and thermostats in the annex controlling a boiler in the main house. There is also the matter of supplying the annex with hot water.

Separate boilers is probably the better solution.

 

[mrbutt]

As for the boiler, I have reservations about supplying everything from the one boiler. You don't say how far the granny annex is from the main house, but there could be a considerable heat loss in the pipes between the two buildings and control systems will get complicated with programmers and thermostats in the annex controlling a boiler in the main house. There is also the matter of supplying the annex with hot water.

Separate boilers is probably the better solution.

The distance between the annex and main house is 4meters. The pipes running between these are already in the ground, however I could possibly lift the outside floor up and re-do the pipes with mega insulation round them.

I generally wont be too fussed with thermostats in the annex and am sure the TRV's should be able to do all the temp adjusting we need. We dont use much heat in there really, only a couple of hours a day on low settings. What I had in mind was sort of 4xZones for different times as we need diff areas on at different times, 1-living rooms, 2-upstairs, 3-leisure rooms, 4-annex, if thats possible?

Supplying the annex with hot water is a bit of a pain. The main hot water demand is with a shower, but we could just fit an electric one there. If we are to lift the floor up outside, we could run a hot water pipe across.

I will see what others say too. I think it would be a shame to fit 2x boilers if 1 could do the job, but maybe 1 can't. Also, the annex only requires 11-12KW and doesn't have natural gas connections.

Also a point to mention is, the length of pipework will be fairly long (using 1 or 2 boilers), would an extra pump be needed or would it be fine?

 

[D_Hailsham]

I could possibly lift the outside floor up and re-do the pipes with mega insulation round them.

If that can be done easily, then it's worth doing.

I generally wont be too fussed with thermostats in the annex and am sure the TRV's should be able to do all the temp adjusting we need. We don't use much heat in there really, only a couple of hours a day on low settings.

You really need a motorized valve to close off the annex when it doesn't need to be heated. The valve could be in the main house, near the boiler, controlled by a wireless programmable thermostat from the annex.

What I had in mind was sort of 4xZones for different times as we need diff areas on at different times, 1-living rooms, 2-upstairs, 3-leisure rooms, 4-annex, if that's possible?

Four zones are possible (plus hot water) each zone would require a motorized valve to shut it off when heating is not required. Each zone would be controlled by a programmable thermostat. Depending on whether you want central control over times, there are several options available. Do a search for Honeywell Evohome.

the length of pipework will be fairly long (using 1 or 2 boilers), would an extra pump be needed or would it be fine?

Although the pipe length has some significance, it's really the number of watts travelling down each pipe which is important. This determines the size of pipe required. Read Small Bore heating Systems and Copper Tubes in Domestic Heating Systems.

The size of pump is determined by the flow rate and the friction loss (head) in the worst (index) circuit. The problem comes when the requirement for the heating circuit conflicts with that for the boiler.

It's probably a good idea to seek the advice of a firm of heating engineers who have experience of large domestic or small commercial installations. Your requirements will be outside the experience of the typical small domestic installer.

 

[D_Hailsham]

Atag Q38S
Vaillant EcoTec 46KW Commercial
Vaillant EcoTec Plus 37KW System
Viessmann Vitodens 200W 45KW Commercial
Broag Remeha Avanta Plus 39C (offer conversion to a system boiler)
Broag Remeha Quinta Pro 45

The Atag, Vaillant 37kW system and Remeha Avanta do not supply the total heat requirement. But if all four zones will never need to be heated at the same time, then they are possible contenders.

 

[mrbutt]

It's probably a good idea to seek the advice of a firm of heating engineers who have experience of large domestic or small commercial installations. Your requirements will be outside the experience of the typical small domestic installer.

Again, thanks for the long explainations, you do the forum proud

Could anybody recommend anybody who is competent at taking this job on AND NOT going to try bankrupt me?

One issue I always have is finding good, decent tradesmen, 70% of them see the size on my house and they try taking me for a fool, charging silly amounts. I dont give the work to them obviously, but it wastes a lot of time filtering out such people.

Thanks all for the help so far

 

[ALEC1]

finding good tradesmen is an art in its own right, and has as much to do with your ability to judge people as anything else..

as to the cost, if you were in Germany you would be paying around three times what you pay in the UK, can any one explain why we command lesser salaries for what is in many cases similar work?

 

[Dan Robinson]

The more you bleat on about getting things as cheap as possible, and how big your house is, the less appealing the prospect is.

Go for the Atag with hot water priority.