Various setup Questions
My setup is as follows.
5 bedroom, 3 storey house
21 rads in total.
Ideal H30 boiler and hot water tank.
Tado wireless receiver to switch boiler on / off.
Tado TRVs on all rads other than bathroom towel radiators.
My first question is around bypass rads. At the moment we are using our bathroom rads as bypass rads, because as I understand it even with a wireless receiver it's possible that if all rooms reach temp the valves will close, the wireless receiver will send a signal to the boiler to shut down, but it may not do so immediately due to minimum run times, and so you have a bypass rad to avoid pump overrun and damage to the boiler? Assuming that's the correct approach, my question is, is there anything more efficient than having a bathroom rad on all day?! We heat a conservatory (daughter's playroom) 4 days a week, and as you can imagine that requires the boiler to run for quite some time so it seems a waste to be heating up a separate rad for that same amount of time (or is it unlikely to account for much usage in the grand scheme of things?!).
My second question is around general efficiency. I know every house and every setup is unique but a post by @eezytiger made me reflect on whether my setup is as efficient as it could be. Currently we only heat the rooms we need heating, by having the max number of rooms able to call for heat individually through the wireless receiver. To give you an example that means right now our lounge, master bedroom, and conservatory are working towards 18°. Other rooms vary between 8° and 14° depending on how often they are used / how long ago they were heated. Is there an argument to say that I would use the same amount of gas, or only marginally more (but have an overall much warmer house), by heating the whole house as described by @eezytiger here: https://community.tado.com/en-gb/discussion/14758/this-guy-killed-entire-tado-value-proposition/p2. I don't know whether this is remotely helpful but on 1 March we used 79 kWh of gas. For context that's heating a lounge at 18° all day, two bedrooms at 18° and 16° overnight (young children), heating a small office for a couple of hours in the morning, and heating hot water for an hour in total. On a day where the conservatory is being used and heated it's more like 105kWh. Is this likely to simply be a consequence of having a decent size house, or am I missing a trick here somewhere?!
My final question is around range rating. I am an absolute novice when it comes to any DIY but I understood this as simply reducing the output on the boiler to thax required for the property. The boiler we have is a H30 so 30kw output. However, with it being a condensing boiler "range rating" in this context would just be turning the dial down, would it not? And given it's also responsible for heating the hot water tank, I think I'm right in saying I can't go any lower than 65° as the hot water then wouldn't be able to heat to the temp required to avoid legionnaires?! Is there anything I can do with the boiler to make it run more efficiently?
Apologies for the long post and thank you in advance for any help you can provide!
Comments
-
I’d suggest getting a professional in.
1 -
Based on your figures the daily energy usage increases by 33% when the conservatory is used. That's a lot of extra energy to heat one extra room. The most energy efficient thing you can do is to stop using this room during the winter months. Conservatories are notorious for losing heat and rarely live up to manufacturer's claims for thermal efficiency.
A bypass radiator in the bathroom will reduce the amount of condensation forming on cold surfaces when someone takes a shower/bath. It takes longer to heat walls/ceilings than to heat the air, so heating the bathroom when it's not in use will have benefits. The extra heat will also dry towels. Moving the bypass radiator to another room probably won't affect efficiency, it's just a question of where you benefit from the unrestricted heat.
The internal walls and ceilings in your home are probably not insulated and are relatively thin compared to your external walls. So their ability to keep heat in a room is limited. When you heat one room the radiator is actually heating the adjacent rooms too. No need to overheat unused rooms, but minimising the temperature difference between rooms can have benefits. Multiple radiators working at the same time will keep the system load above the minimum load for the boiler. Your boiler can modulate down to 6KW, if the radiator load is smaller than this the boiler won't be able to maintain the flow temperature. It will switch off to avoid overheating and then come back on when the water in the pipes has cooled. This process is called short cycling and will waste energy. Far better for the boiler to run at a low output for as long as possible.
With a system boiler it's best to keep a minimum flow temp of 65°C for the reasons you state. Some boilers can be configured to have a high temperature for the cylinder and a lower temperature for heating only, but few systems work in this manner.
Range rating will reduce the maximum output, but won't alter the flow temperature (unless set too low). Range rating is only going to be effective at startup when the boiler will initially run with a high output to quickly heat the water. Once the water in the pipes approaches the target of 65°C it will lower its output to maintain a constant water temperature. With 21 radiators and a cylinder working you'll probably need close to the 30KW on a cold day.
If you measure each of your radiators and count the number of panels (single/double), plus the number of fins, then you should be able to find similar radiators online and determine the heat output for the radiator. Do this for each radiator and you will have the maximum heat output for the property. You can also get a professional to calculate the 'whole home heat loss' in KW. If your property is newish then I'd expect the whole home heat loss value to be close to the total radiator output. Builders are meant to do these calculations for each home that they build. The days of throwing in a big boiler and some random radiators should be a thing of the past.
0 -
First question. A bypass is only needed for the boiler to dissipate excess heat. That could be internal to the boiler, an external bypass valve, or a rad. Conversely a radiator bypass pushes heat into your home.
second, we only heat rooms as we need. Our 12 month experience has helped us to reduce energy use by 35% vs CET. In comparison, ‘This guy’ does not reflect our use or energy savings.
As for range rating, our only comment is the time our hot water is ‘on’.. A ‘hot’ shower needs nearly 60 minutes to heat the hot water tank. Anything less than 30 minute is ‘phew, that’s chilly’.
0 -
@Montage thank you - a fair assessment I think!
@GrilledCheese2 thank you. Unfortunately we use the conservatory as a playroom so as much as I'd love to save a bit of money, it would be at the expense of my sanity if the playroom was out of use!
Thank you also for confirming on the other bits. I'm glad to hear that the bathroom is as good a place as any to have a bypass rad.
@wateroakley thank you.0
