Room temperatures

[Jamesplumber92]

Can you get your room temperatures right (19° for a bedroom, 21° for a living room etc) right without room stats.

Is the desired temperature taken into account when sizing radiators?

 

[SJB060685]

This is all part of your heat calculations mate. You would take design outside temperature (varies from location throughout the country) and your target room temperature. Use this as a basis and with lots of other data you will arrive at the output required for each room. To answer your question though, yes you can.

 

[Jamesplumber92]

This is all part of your heat calculations mate. You would take design outside temperature (varies from location throughout the country) and your target room temperature. Use this as a basis and with lots of other data you will arrive at the output required for each room. To answer your question though, yes you can.

Cheers! Would plumbers usually carry out these calculations? My Customer doesn't have drawings to go off. The supplier said they'll size everything so Ive measured up the rooms and windows but I didn't go as far as looking at Insulation and stuff like that

 

[SJB060685]

Cheers! Would plumbers usually carry out these calculations? My Customer doesn't have drawings to go off. The supplier said they'll size everything so Ive measured up the rooms and windows but I didn't go as far as looking at Insulation and stuff like that

To be honest this is something you should be familiar with and shouldn't rely on other parties to undertake for you, although I appreciate you are not familiar with it. You need to know the U values of materials for calculating the fabric heat loss and you need to know the amount of air changes per hour for calculating the ventilation heat loss. It is a time consuming task if doing by hand but there are a number of softwares that can help you, most notably heatengineer.com. There are other means of getting rough ideas but they are not accurate.

 

[exedon2]

I have always done our own heat loss calculations long hand back in the day!
Use stelrad stars now its cloud based probably got to have a reasonable understanding of heat loss calculations to get best from it.

 

[Jamesplumber92]

I have always done our own heat loss calculations long hand back in the day!
Use stelrad stars now its cloud based probably got to have a reasonable understanding of heat loss calculations to get best from it.

I've had a look at stelrads and some of it seems simple (though it keeps crashing!) but I've a feeling I'm missing some important info.

They have a basic and an advanced calculator, I take it you always use advanced?

What's the margin of error like when calculating these requirements? I'm tempted to leave get the supplier to do as they have the xp. At the same time they may rush through. There's details I don't want them to miss as I've set myself the goal of getting the return temperature right so the boiler will always run in condensing mode

 

[SJB060685]

Doing an accurate heat loss calculation takes time by hand. As I mentioned before the best software would probably be heatengineer.com but you will need to know certain things about the buildings fabric before you can even start really.
The return temperature for kerosene needs to be about 47°c, quite a bit lower than mains gas. Your boiler and system should be set up for a flow rate to achieve a DT of 20°c, this means your flow temperature will be around 67°c and the mean water temperature of the radiators will be at 57°c. This means you will need to work out the correction factors for sizing rads.
This really is quite a complicated task and is a bit difficult to explain through text.

 

[Jamesplumber92]

Doing an accurate heat loss calculation takes time by hand. As I mentioned before the best software would probably be heatengineer.com but you will need to know certain things about the buildings fabric before you can even start really.
The return temperature for kerosene needs to be about 47°c, quite a bit lower than mains gas. Your boiler and system should be set up for a flow rate to achieve a DT of 20°c, this means your flow temperature will be around 67°c and the mean water temperature of the radiators will be at 57°c. This means you will need to work out the correction factors for sizing rads.
This really is quite a complicated task and is a bit difficult to explain through text.

Ok, I've emailed the supplier and asked what info they need. If the ask for the info you've mentioned above I'll know they're legit, if not I'll soldier on and work through the calculation myself.

Have you done this for many houses?

 

[SJB060685]

I'm actually off work and have been for some time, for reasons I won't go into on here. These calculations need to be done on EVERY new installation or boiler replacement, especially if changes have been made to the properties insulation of the years.
You need to know the U values for the various building materials and air changes per hour, a long with room sizes and design outside temperatures and target inside temperatures for the rooms. Once you've done it a few times it doesn't take too long to calculate but as I said you NEED to know certain data beforehand, or you'll never arrive at the correct requirements.

 

[Jamesplumber92]

I'm actually off work and have been for some time, for reasons I won't go into on here. These calculations need to be done on EVERY new installation or boiler replacement, especially if changes have been made to the properties insulation of the years.
You need to know the U values for the various building materials and air changes per hour, a long with room sizes and design outside temperatures and target inside temperatures for the rooms. Once you've done it a few times it doesn't take too long to calculate but as I said you NEED to know certain data beforehand, or you'll never arrive at the correct requirements.

That's fair enough, I'll take a drive back to see the owner and go through what materials are being used.

For an open plan living room and kitchen would you class them as one room or would you separate them. I know they have different desired temperatures but I'd say it'd be hard to achieve.