MVHR - list of questions/thoughts

[PeterW]

4 minutes ago, Bramco said:

 

This is something that has got me thinking.

 

Assuming we have our bathrooms warmer than the rest of the house and also have heated towel rails in the bathrooms, won't the returned warmth that an MVHR recovers as the air flows from the living spaces through the bathrooms to the outside keep the living spaces warm. 

 

So you can imagine that the heated towel rails are actually doing the heating which if these are electric are at a COP of 1....    

 

Is this an issue? And if so how do you prevent it happening.

 

Simon

airflow is so low, and the exhaust will be mixed from non heated rooms such as kitchens and utility rooms that the increase in output temperature will be borderline 1-2c at most. With a maximum 85% efficiency you’ll be getting very little additional heat effect back. 

[Ferdinand]

26 minutes ago, Bramco said:

 

This is something that has got me thinking.

 

Assuming we have our bathrooms warmer than the rest of the house and also have heated towel rails in the bathrooms, won't the returned warmth that an MVHR recovers as the air flows from the living spaces through the bathrooms to the outside keep the living spaces warm. 

 

So you can imagine that the heated towel rails are actually doing the heating which if these are electric are at a COP of 1....    

 

Is this an issue? And if so how do you prevent it happening.

 

Simon

 

The purpose of electric towel rails is, I think, for most people in near-PH houses or better, to provide a boost when needed, or even as an insurance policy if the upstairs turns out to need a bit of heat from time to time and they decided to have just that.

 

If you were more sure that it would be necessary then you could plumb it in to the general system, just as happens for normal installation. Even as its own zone.

 

Mine are on my main gas circuit (have ufh downstairs and rads upstairs with a boiler) but for both bathrooms are plumbed into the upstairs circuit - perhaps they thought plumbing in to the ufh was not acceptable.

 

F 

[joe90]

My electric towel rads are used fir warm towels / dry towels and make the room a little warmer when you take your clothes off , mine are on timers fir the beginning and end of the day, too much hassle to plumb them into downstairs UFH for the short periods they are on. MVHR is unlikely to shift any noticeable heat from these rooms.

[Gone West]

1 hour ago, Bramco said:

 

This is something that has got me thinking.

 

Assuming we have our bathrooms warmer than the rest of the house and also have heated towel rails in the bathrooms, won't the returned warmth that an MVHR recovers as the air flows from the living spaces through the bathrooms to the outside keep the living spaces warm. 

 

So you can imagine that the heated towel rails are actually doing the heating which if these are electric are at a COP of 1....    

 

Is this an issue? And if so how do you prevent it happening.

 

Simon

This is how I heat my house which is in the SE England near the coast and has an extremely low heat requirement. I have an electric towel rail in each of the three bathrooms, which in the winter, keeps those rooms at around 24C and provides warm air for the MVHR to circulate around the house keeping it at 23C. If more heat is required there is an EASHP built into the MVHR unit which boosts the temperature of the supply air a little more. This form of heating would not work in anything other than a very low energy PH.

[Ferdinand]

48 minutes ago, joe90 said:

My electric towel rads are used fir warm towels / dry towels and make the room a little warmer when you take your clothes off , mine are on timers fir the beginning and end of the day, too much hassle to plumb them into downstairs UFH for the short periods they are on. MVHR is unlikely to shift any noticeable heat from these rooms.

 

That probably illustrates the difference between very well insulated and well-but-not-brilliant houses - my walls are about 0.2 u-value, and floor a perhaps 0.18. Joe's is better I think.

 

I use my plumbed in towel rail for basic heat in the downstairs bathroom (all upstairs Rads are off), but also with downstairs ufh on (really its a bit light on deliver-ability for very cold weather due to lower insulation than passive). All on timers. I open the bathroom for a boost after a morning 10 minute blow-through. Were I building it I would do it with more insulation, but it was already done. 

 

What you need is an appropriate setup for your chosen specification, plus a suitable strategy that will cope if you got your calculations a bit off.

 

Ferdinand

 

 

 

 

[ProDave]

3 minutes ago, Ferdinand said:

What you need is an appropriate setup for your chosen specification, plus aa suitable strategy that will cope if you got your calculations a bit off.

 

Ferdinand

 

Several of us put in an electric point in each bedroom just in case we needed a small electric panel heater.  I don't know of anyone who has actually used that and installed a heater.

[Bramco]

4 minutes ago, ProDave said:

Several of us put in an electric point in each bedroom just in case we needed a small electric panel heater.  I don't know of anyone who has actually used that and installed a heater.

We were intending to do that as well on the first floor. So only UFH in the slab on the ground floor.